diff --git a/main/Act.scala b/main/Act.scala
index dcb3e34fb..43ab23a6f 100644
--- a/main/Act.scala
+++ b/main/Act.scala
@@ -5,7 +5,6 @@ package sbt
 
 	import Project.ScopedKey
 	import Keys.{sessionSettings, thisProject}
-	import CommandSupport.logger
 	import Load.BuildStructure
 	import complete.{DefaultParsers, Parser}
 	import DefaultParsers._
diff --git a/main/Aggregation.scala b/main/Aggregation.scala
index a427ffbe2..ac8b0e345 100644
--- a/main/Aggregation.scala
+++ b/main/Aggregation.scala
@@ -77,7 +77,7 @@ final object Aggregation
 			import std.TaskExtra._
 		val toRun = ts map { case KeyValue(k,t) => t.map(v => KeyValue(k,v)) } join;
 		val start = System.currentTimeMillis
-		val result = withStreams(structure){ str => runTask(toRun)(nodeView(s, str, extra.tasks, extra.values)) }
+		val result = withStreams(structure){ str => runTask(toRun, str)(nodeView(s, str, extra.tasks, extra.values)) }
 		val stop = System.currentTimeMillis
 		val log = logger(s)
 		lazy val extracted = Project.extract(s)
diff --git a/main/Build.scala b/main/Build.scala
index 3e654a121..3e1aa36c3 100644
--- a/main/Build.scala
+++ b/main/Build.scala
@@ -11,7 +11,7 @@ package sbt
 	import collection.mutable
 	import Compiler.{Compilers,Inputs}
 	import Project.{inScope, ScopedKey, ScopeLocal, Setting}
-	import Keys.{appConfiguration, baseDirectory, configuration, thisProject, thisProjectRef}
+	import Keys.{appConfiguration, baseDirectory, configuration, streams, thisProject, thisProjectRef}
 	import TypeFunctions.{Endo,Id}
 	import tools.nsc.reporters.ConsoleReporter
 	import Build.{analyzed, data}
@@ -108,10 +108,11 @@ object EvaluateTask
 	import BuildStreams.{Streams, TaskStreams}
 	
 	val SystemProcessors = Runtime.getRuntime.availableProcessors
-	
+
+	val isDummyTask = AttributeKey[Boolean]("is-dummy-task")
+	val taskDefinitionKey = AttributeKey[ScopedKey[_]]("task-definition-key")
 	val (state, dummyState) = dummy[State]("state")
 	val (streamsManager, dummyStreamsManager) = dummy[Streams]("streams-manager")
-	val streams = TaskKey[TaskStreams]("streams")
 	val resolvedScoped = SettingKey[ScopedKey[_]]("resolved-scoped")
 	private[sbt] val parseResult: TaskKey[_] = TaskKey("$parse-result")
 
@@ -121,7 +122,12 @@ object EvaluateTask
 	)
 	
 	def dummy[T](name: String): (TaskKey[T], Task[T]) = (TaskKey[T](name), dummyTask(name))
-	def dummyTask[T](name: String): Task[T] = task( error("Dummy task '" + name + "' did not get converted to a full task.") ) named name
+	def dummyTask[T](name: String): Task[T] =
+	{
+		val base: Task[T] = task( error("Dummy task '" + name + "' did not get converted to a full task.") ) named name
+		base.copy(info = base.info.set(isDummyTask, true))
+	}
+	def isDummy(t: Task[_]): Boolean = t.info.attributes.get(isDummyTask) getOrElse false
 
 	def evalPluginDef(log: Logger)(pluginDef: BuildStructure, state: State): Seq[Attributed[File]] =
 	{
@@ -134,9 +140,22 @@ object EvaluateTask
 	def evaluateTask[T](structure: BuildStructure, taskKey: ScopedKey[Task[T]], state: State, ref: ProjectRef, checkCycles: Boolean = false, maxWorkers: Int = SystemProcessors): Option[Result[T]] =
 		withStreams(structure) { str =>
 			for( (task, toNode) <- getTask(structure, taskKey, state, str, ref) ) yield
-				runTask(task, checkCycles, maxWorkers)(toNode)
+				runTask(task, str, checkCycles, maxWorkers)(toNode)
 		}
-
+	def logIncResult(result: Result[_], streams: Streams) = result match { case Inc(i) => logIncomplete(i, streams); case _ => () }
+	def logIncomplete(result: Incomplete, streams: Streams)
+	{
+		val log = streams(ScopedKey(GlobalScope, Keys.logged)).log
+		val all = for(Incomplete(Some(key: Project.ScopedKey[_]), _, msg, _, ex) <- Incomplete linearize result) yield (key, msg, ex)
+		for( (key, _, Some(ex)) <- all)
+			getStreams(key, streams).log.trace(ex)
+		log.error("Incomplete task(s):")
+		for( (key, msg, ex) <- all if(msg.isDefined || ex.isDefined) )
+			getStreams(key, streams).log.error("  " + Project.display(key) + ": " + (msg.toList ++ ex.toList).mkString("\n\t"))
+		log.error("Run 'last <task>' for the full log(s).")
+	}
+	def getStreams(key: ScopedKey[_], streams: Streams): TaskStreams =
+		streams(ScopedKey(Project.fillTaskAxis(key).scope, Keys.streams.key))
 	def withStreams[T](structure: BuildStructure)(f: Streams => T): T =
 	{
 		val str = std.Streams.closeable(structure.streams)
@@ -153,13 +172,25 @@ object EvaluateTask
 	def nodeView[HL <: HList](state: State, streams: Streams, extraDummies: KList[Task, HL] = KNil, extraValues: HL = HNil): Execute.NodeView[Task] =
 		Transform(dummyStreamsManager :^: KCons(dummyState, extraDummies), streams :+: HCons(state, extraValues))
 
-	def runTask[Task[_] <: AnyRef, T](root: Task[T], checkCycles: Boolean = false, maxWorkers: Int = SystemProcessors)(implicit taskToNode: Execute.NodeView[Task]): Result[T] =
+	def runTask[Task[_] <: AnyRef, T](root: Task[T], streams: Streams, checkCycles: Boolean = false, maxWorkers: Int = SystemProcessors)(implicit taskToNode: Execute.NodeView[Task]): Result[T] =
 	{
 		val (service, shutdown) = CompletionService[Task[_], Completed](maxWorkers)
 
 		val x = new Execute[Task](checkCycles)(taskToNode)
-		try { x.run(root)(service) } finally { shutdown() }
+		val result = try { x.run(root)(service) } finally { shutdown() }
+		val replaced = transformInc(result)
+		logIncResult(replaced, streams)
+		replaced
 	}
+	def transformInc[T](result: Result[T]): Result[T] =
+		result.toEither.left.map { i =>
+			Incomplete.transform(i) {
+				case in @ Incomplete(Some(node: Task[_]), _, _, _, _) => in.copy(node = transformNode(node))
+				case _ => i
+			}
+		}
+	def transformNode(node: Task[_]): Option[ScopedKey[_]] =
+		node.info.attributes get taskDefinitionKey
 
 	def processResult[T](result: Result[T], log: Logger, show: Boolean = false): T =
 		onResult(result, log) { v => if(show) println("Result: " + v); v }
@@ -167,9 +198,7 @@ object EvaluateTask
 		result match
 		{
 			case Value(v) => f(v)
-			case Inc(inc) =>
-				log.error(Incomplete.show(inc, true))
-				error("Task did not complete successfully")
+			case Inc(inc) => throw inc
 		}
 
 	// if the return type Seq[Setting[_]] is not explicitly given, scalac hangs
@@ -287,7 +316,7 @@ object Load
 	// additionally, set the task axis to the defining key if it is not set
 	def finalTransforms(ss: Seq[Setting[_]]): Seq[Setting[_]] =
 	{
-		import EvaluateTask.{parseResult, resolvedScoped, streams}
+		import EvaluateTask.{parseResult, resolvedScoped}
 		def isSpecial(key: AttributeKey[_]) = key == streams.key || key == resolvedScoped.key || key == parseResult.key
 		def mapSpecial(to: ScopedKey[_]) = new (ScopedKey ~> ScopedKey){ def apply[T](key: ScopedKey[T]) =
 			if(isSpecial(key.key))
@@ -298,7 +327,11 @@ object Load
 			}
 			else key
 		}
-		ss.map(s => s mapReferenced mapSpecial(s.key) )
+		def setDefining[T] = (key: ScopedKey[T], value: T) => value match {
+			case tk: Task[t] if !EvaluateTask.isDummy(tk) => Task(tk.info.set(EvaluateTask.taskDefinitionKey, key), tk.work).asInstanceOf[T]
+			case _ => value
+		}
+		ss.map(s => s mapReferenced mapSpecial(s.key) mapInit setDefining )
 	}
 
 	def structureIndex(settings: Settings[Scope]): StructureIndex =
diff --git a/main/CommandSupport.scala b/main/CommandSupport.scala
index 675692877..ea765ff2a 100644
--- a/main/CommandSupport.scala
+++ b/main/CommandSupport.scala
@@ -41,21 +41,22 @@ EvalCommand + """ <expression>
 	Evaluates the given Scala expression and prints the result and type.
 """
 
+	val LastCommand = "last"
 	val LastGrepCommand = "last-grep"
+
 	val lastGrepBrief = (LastGrepCommand + " <pattern> <key>", "Shows lines from the last output for 'key' that match 'pattern'.")
 	val lastGrepDetailed = 
 LastGrepCommand + """ <pattern> <key>
 
-	<pattern> is a regular expression interpreted by java.util.Pattern
+	<pattern> is a regular expression interpreted by java.util.Pattern.
 	Lines that match 'pattern' from the last streams output associated with the key are displayed.
 	See also """ + LastCommand + "."
 
-	val LastCommand = "last"
 	val lastBrief = (LastCommand + " <key>", "Prints the last output associated with 'key'.")
 	val lastDetailed = 
 LastCommand + """ <key>
 
-	The last streams output associated with the key (typically a task key) is redisplayed.
+	Redisplays the last streams output associated with the key (typically a task key).
 	See also """ + LastGrepCommand + "."
 
 	val InspectCommand = "inspect"
diff --git a/main/Defaults.scala b/main/Defaults.scala
index 3a8330402..382768a58 100755
--- a/main/Defaults.scala
+++ b/main/Defaults.scala
@@ -8,7 +8,7 @@ package sbt
 	import compiler.Discovery
 	import Project.{inConfig, Initialize, inScope, inTask, ScopedKey, Setting}
 	import Configurations.{Compile => CompileConf, Test => TestConf}
-	import EvaluateTask.{resolvedScoped, streams}
+	import EvaluateTask.resolvedScoped
 	import complete._
 	import std.TaskExtra._
 
diff --git a/main/Keys.scala b/main/Keys.scala
index 6517e947a..23ddcad91 100644
--- a/main/Keys.scala
+++ b/main/Keys.scala
@@ -4,7 +4,7 @@
 package sbt
 
 	import java.io.File
-	import EvaluateTask.{resolvedScoped, streams}
+	import EvaluateTask.resolvedScoped
 	import complete._
 	import inc.Analysis
 	import std.TaskExtra._
@@ -19,6 +19,7 @@ object Keys
 	val logLevel = SettingKey[Level.Value]("log-level")
 	val persistLogLevel = SettingKey[Level.Value]("persist-log-level")
 	val traceLevel = SettingKey[Int]("trace-level")
+	val persistTraceLevel = SettingKey[Int]("persist-trace-level")
 	val showSuccess = SettingKey[Boolean]("show-success")
 	val showTiming = SettingKey[Boolean]("show-timing")
 	val timingFormat = SettingKey[java.text.DateFormat]("timing-format")
@@ -201,4 +202,5 @@ object Keys
 
 	// special
 	val settings = TaskKey[Settings[Scope]]("settings")
+	val streams = TaskKey[BuildStreams.TaskStreams]("streams")
 }
\ No newline at end of file
diff --git a/main/LogManager.scala b/main/LogManager.scala
index 8d1a6afc0..5a0960847 100644
--- a/main/LogManager.scala
+++ b/main/LogManager.scala
@@ -7,16 +7,18 @@ package sbt
 	import LogManager._
 	import std.Transform
 	import Project.ScopedKey
-	import Keys.{logLevel, persistLogLevel}
+	import Keys.{logLevel, persistLogLevel, persistTraceLevel, traceLevel}
 
 object LogManager
 {
 	def construct(data: Settings[Scope]) = (task: ScopedKey[_], to: PrintWriter) =>
 	{
 		val scope = task.scope
-		def level(key: AttributeKey[Level.Value], default: Level.Value): Level.Value = data.get(scope, key) getOrElse default
-		val screenLevel = level(logLevel.key, Level.Info)
-		val backingLevel = level(persistLogLevel.key, Level.Debug)
+		def getOr[T](key: AttributeKey[T], default: T): T = data.get(scope, key) getOrElse default
+		val screenLevel = getOr(logLevel.key, Level.Info)
+		val backingLevel = getOr(persistLogLevel.key, Level.Debug)
+		val screenTrace = getOr(traceLevel.key, -1)
+		val backingTrace = getOr(persistTraceLevel.key, Int.MaxValue)
 
 		val console = ConsoleLogger()
 		val backed = ConsoleLogger(ConsoleLogger.printWriterOut(to), useColor = false) // TODO: wrap this with a filter that strips ANSI codes
@@ -27,6 +29,8 @@ object LogManager
 			// set the specific levels
 		console setLevel screenLevel
 		backed setLevel backingLevel
+		console setTrace screenTrace
+		backed setTrace backingTrace
 		multi: Logger
 	}
 }
\ No newline at end of file
diff --git a/main/Main.scala b/main/Main.scala
index c3477e335..05787a417 100644
--- a/main/Main.scala
+++ b/main/Main.scala
@@ -323,10 +323,17 @@ object BuiltinCommands
 		Project.setProject(session, structure, s)
 	}
 	
-	def handleException(e: Throwable, s: State, trace: Boolean = true): State = {
-		val log = logger(s)
-		if(trace) log.trace(e)
-		log.error(e.toString)
+	def handleException(e: Throwable, s: State): State =
+		handleException(e, s, logger(s))
+	def handleException(e: Throwable, s: State, log: Logger): State =
+	{
+		e match
+		{
+			case i: Incomplete => () // already handled by evaluateTask
+			case _ =>
+				log.trace(e)
+				log.error(e.toString)
+		}
 		s.fail
 	}
 	
diff --git a/main/Project.scala b/main/Project.scala
index 11fb7a21b..16b57e242 100644
--- a/main/Project.scala
+++ b/main/Project.scala
@@ -8,7 +8,7 @@ package sbt
 	import Project._
 	import Types.Endo
 	import Keys.{appConfiguration, buildStructure, commands, configuration, historyPath, projectCommand, sessionSettings, shellPrompt, thisProject, thisProjectRef, watch}
-	import Scope.ThisScope
+	import Scope.{GlobalScope,ThisScope}
 	import CommandSupport.logger
 	import compiler.Eval
 
@@ -72,6 +72,7 @@ object Project extends Init[Scope]
 	def getOrError[T](state: State, key: AttributeKey[T], msg: String): T = state get key getOrElse error(msg)
 	def structure(state: State): Load.BuildStructure = getOrError(state, buildStructure, "No build loaded.")
 	def session(state: State): SessionSettings = getOrError(state, sessionSettings, "Session not initialized.")
+
 	def extract(state: State): Extracted =
 	{
 		val se = session(state)
diff --git a/tasks/Execute.scala b/tasks/Execute.scala
index f2955ac55..ba7028b6e 100644
--- a/tasks/Execute.scala
+++ b/tasks/Execute.scala
@@ -201,11 +201,6 @@ final class Execute[A[_] <: AnyRef](checkCycles: Boolean)(implicit view: NodeVie
 		reverse(node) = Seq()
 		viewCache.getOrUpdate(node, view(node))
 	}
-	def incomplete(in: A[_]): Option[(A[_], Incomplete)] =
-		results(in) match {
-			case Value(v) => None
-			case Inc(inc) => Some( (in, inc) )
-		}
 		/** Send the work for this node to the provided Strategy. */
 	def submit[T]( node: A[T] )(implicit strategy: Strategy)
 	{
@@ -219,8 +214,8 @@ final class Execute[A[_] <: AnyRef](checkCycles: Boolean)(implicit view: NodeVie
 	def work[T](node: A[T], f: => Either[A[T], T])(implicit strategy: Strategy): Completed =
 	{
 		val result = wideConvert(f).left.map {
-			case i: Incomplete => i
-			case e => Incomplete(Incomplete.Error, directCause = Some(e))
+			case i: Incomplete => if(i.node.isEmpty) i.copy(node = Some(node)) else i
+			case e => Incomplete(Some(node), Incomplete.Error, directCause = Some(e))
 		}
 		completed {
 			result match {
@@ -304,7 +299,7 @@ final class Execute[A[_] <: AnyRef](checkCycles: Boolean)(implicit view: NodeVie
 		allCallers(node)
 		if(all contains target) cyclic(node, target, "Cyclic reference")
 	}
-	def cyclic[T](caller: A[T], target: A[T], msg: String) = throw new Incomplete(message = Some(msg), directCause = Some( new CyclicException(caller, target, msg) ) )
+	def cyclic[T](caller: A[T], target: A[T], msg: String) = throw new Incomplete(Some(caller), message = Some(msg), directCause = Some( new CyclicException(caller, target, msg) ) )
 	final class CyclicException[T](val caller: A[T], val target: A[T], msg: String) extends Exception(msg)
 
 		// state testing
diff --git a/tasks/Incomplete.scala b/tasks/Incomplete.scala
index c3fa5fc23..28c30ef8c 100644
--- a/tasks/Incomplete.scala
+++ b/tasks/Incomplete.scala
@@ -4,31 +4,47 @@
 package sbt
 
 import Incomplete.{Error, Value => IValue}
-final case class Incomplete(tpe: IValue = Error, message: Option[String] = None, causes: Seq[Incomplete] = Nil, directCause: Option[Throwable] = None)
-	extends Exception(message.orNull, directCause.orNull)
+final case class Incomplete(node: Option[AnyRef], tpe: IValue = Error, message: Option[String] = None, causes: Seq[Incomplete] = Nil, directCause: Option[Throwable] = None)
+	extends Exception(message.orNull, directCause.orNull) {
+		override def toString = "Incomplete(node=" + node + ", tpe=" + tpe + ", msg=" + message + ", causes=" + causes + ", directCause=" + directCause +")"
+}
 
 object Incomplete extends Enumeration {
 	val Skipped, Error = Value
-	def show(i: Incomplete, traces: Boolean): String =
+	
+	def transform(i: Incomplete)(f: Incomplete => Incomplete): Incomplete =
 	{
-		val exceptions = allExceptions(i)
-		val traces = exceptions.map(ex => ex.getStackTrace.mkString(ex.toString + "\n\t", "\n\t", "\n"))
-		val causeStr = if(i.causes.isEmpty) "" else (i.causes.length + " cause(s)")
-		"Incomplete (" + show(i.tpe) + ") " + i.message.getOrElse("") + causeStr + "\n" + traces
-	}
+			import collection.JavaConversions._
+		val visited: collection.mutable.Map[Incomplete,Incomplete] = new java.util.IdentityHashMap[Incomplete, Incomplete]
+		def visit(inc: Incomplete): Incomplete =
+			visited.getOrElseUpdate(inc, visitCauses(f(inc)) )
+		def visitCauses(inc: Incomplete): Incomplete =
+			inc.copy(causes = inc.causes.map(visit) )
 
-	def allExceptions(is: Seq[Incomplete]): Iterable[Throwable] =
-		allExceptions(new Incomplete(causes = is))
-	def allExceptions(i: Incomplete): Iterable[Throwable] =
+		visit(i)
+	}
+	def visitAll(i: Incomplete)(f: Incomplete => Unit)
 	{
-		val exceptions = IDSet.create[Throwable]
 		val visited = IDSet.create[Incomplete]
 		def visit(inc: Incomplete): Unit =
 			visited.process(inc)( () ) {
-				exceptions ++= inc.directCause.toList
+				f(inc)
 				inc.causes.foreach(visit)
 			}
 		visit(i)
+	}
+	def linearize(i: Incomplete): Seq[Incomplete] =
+	{
+		var ordered = List[Incomplete]()
+		visitAll(i) { ordered ::= _ }
+		ordered
+	}
+	def allExceptions(is: Seq[Incomplete]): Iterable[Throwable] =
+		allExceptions(new Incomplete(None, causes = is))
+	def allExceptions(i: Incomplete): Iterable[Throwable] =
+	{
+		val exceptions = IDSet.create[Throwable]
+		visitAll(i) { exceptions ++= _.directCause.toList }
 		exceptions.all
 	}
 	def show(tpe: Value) = tpe match { case Skipped=> "skipped"; case Error => "error" }
diff --git a/tasks/Result.scala b/tasks/Result.scala
index 99b6a2b07..8ad99d5c0 100644
--- a/tasks/Result.scala
+++ b/tasks/Result.scala
@@ -36,4 +36,8 @@ object Result
 		r foreach tryValue[Unit]
 		tryValue[S](v)
 	}
+	implicit def fromEither[T](e: Either[Incomplete, T]): Result[T] = e match {
+		case Left(i) => Inc(i)
+		case Right(v) => Value(v)
+	}
 }
\ No newline at end of file
diff --git a/tasks/standard/TaskExtra.scala b/tasks/standard/TaskExtra.scala
index 66bab1ca1..613cb6310 100644
--- a/tasks/standard/TaskExtra.scala
+++ b/tasks/standard/TaskExtra.scala
@@ -206,20 +206,22 @@ object TaskExtra extends TaskExtra
 	}
 	def failM[T]: Result[T] => Incomplete = { case Inc(i) => i; case x => expectedFailure }
 
-	def expectedFailure = throw Incomplete(message = Some("Expected failure"))
+	def expectedFailure = throw Incomplete(None, message = Some("Expected dependency to fail."))
 
 	def successM[T]: Result[T] => T = { case Inc(i) => throw i; case Value(t) => t }
 	def allM[In <: HList]: Results[In] => In = in =>
 	{
 		val incs = failuresM(in)
-		if(incs.isEmpty) in.down(Result.tryValue) else throw Incomplete(causes = incs)
+		if(incs.isEmpty) in.down(Result.tryValue) else throw incompleteDeps(incs)
 	}
 	def failuresM[In <: HList]: Results[In] => Seq[Incomplete] = x => failures[Any](x.toList)
 
 	def all[D](in: Seq[Result[D]]) =
 	{
 		val incs = failures(in)
-		if(incs.isEmpty) in.map(Result.tryValue.fn[D]) else throw Incomplete(causes = incs)
+		if(incs.isEmpty) in.map(Result.tryValue.fn[D]) else throw incompleteDeps(incs)
 	}
 	def failures[A](results: Seq[Result[A]]): Seq[Incomplete] = results.collect { case Inc(i) => i }
+
+	def incompleteDeps(incs: Seq[Incomplete]): Incomplete = Incomplete(None, message = Some("Dependency did not complete successfully."), causes = incs)
 }
\ No newline at end of file
diff --git a/util/collection/Settings.scala b/util/collection/Settings.scala
index ef6261c51..9450ee10e 100644
--- a/util/collection/Settings.scala
+++ b/util/collection/Settings.scala
@@ -180,6 +180,7 @@ trait Init[Scope]
 		def dependsOn: Seq[ScopedKey[_]] = remove(init.dependsOn, key)
 		def mapReferenced(g: MapScoped): Setting[T] = new Setting(key, init mapReferenced g)
 		def mapKey(g: MapScoped): Setting[T] = new Setting(g(key), init)
+		def mapInit(f: (ScopedKey[T], T) => T): Setting[T] = new Setting(key, init.map(t => f(key,t)))
 		override def toString = "setting(" + key + ")"
 	}