diff --git a/interface/src/main/java/xsbti/Versions.java b/interface/src/main/java/xsbti/Versions.java
deleted file mode 100644
index 122499c04..000000000
--- a/interface/src/main/java/xsbti/Versions.java
+++ /dev/null
@@ -1,11 +0,0 @@
-/* sbt -- Simple Build Tool
- * Copyright 2009  Mark Harrah
- */
-package xsbti;
-
-public interface Versions
-{
-	public static final String Sbt = "0.7.0_13"; // keep in sync with LauncherProject in the XSbt project definition;
-	public static final int Interface = 1;
-	public static final int BootInterface = 1;
-}
diff --git a/ivy/ComponentManager.scala b/ivy/ComponentManager.scala
index 0056ace7a..fc4606f6d 100644
--- a/ivy/ComponentManager.scala
+++ b/ivy/ComponentManager.scala
@@ -55,7 +55,7 @@ class ComponentManager(globalLock: xsbti.GlobalLock, provider: xsbti.ComponentPr
 	/** Retrieve the file for component 'id' from the local repository. */
 	private def update(id: String): Unit = IvyCache.withCachedJar(sbtModuleID(id), log)(jar => define(id, Seq(jar)) )
 
-	private def sbtModuleID(id: String) = ModuleID("org.scala-tools.sbt", id, xsbti.Versions.Sbt)
+	private def sbtModuleID(id: String) = ModuleID("org.scala-tools.sbt", id, ComponentManager.stampedVersion)
 	/** Install the files for component 'id' to the local repository.  This is usually used after writing files to the directory returned by 'location'. */
 	def cache(id: String): Unit = IvyCache.cacheJar(sbtModuleID(id), file(id)(IfMissing.Fail), log)
 	def clearCache(id: String): Unit = lockGlobalCache { IvyCache.clearCachedJar(sbtModuleID(id), log) }
@@ -69,4 +69,15 @@ object IfMissing
 {
 	object Fail extends IfMissing
 	final class Define(val cache: Boolean, define: => Unit) extends IfMissing { def apply() = define }
+}
+object ComponentManager
+{
+	lazy val (version, timestamp) =
+	{
+		val properties = new java.util.Properties
+		val propertiesStream = getClass.getResourceAsStream("/xsbt.version.properties")
+		try { properties.load(propertiesStream) } finally { propertiesStream.close() }
+		(properties.getProperty("version"), properties.getProperty("timestamp"))
+	}
+	lazy val stampedVersion = version + "_" + timestamp
 }
\ No newline at end of file
diff --git a/ivy/IvyCache.scala b/ivy/IvyCache.scala
index e3f0044bc..cfb829458 100644
--- a/ivy/IvyCache.scala
+++ b/ivy/IvyCache.scala
@@ -52,8 +52,7 @@ object IvyCache
 			copyTo
 		}
 
-	/** Get the location of the cached jar for the given ID in the Ivy cache.  If the jar is not in the cache, NotInCache is thrown
-	* TODO: locking.*/
+	/** Get the location of the cached jar for the given ID in the Ivy cache.  If the jar is not in the cache, NotInCache is thrown .*/
 	def withCachedJar[T](id: ModuleID, log: IvyLogger)(f: File => T): T =
 	{
 		val cachedFile =
diff --git a/launch/src/test/scala/ScalaProviderTest.scala b/launch/src/test/scala/ScalaProviderTest.scala
index b324d7f39..2071b3773 100644
--- a/launch/src/test/scala/ScalaProviderTest.scala
+++ b/launch/src/test/scala/ScalaProviderTest.scala
@@ -73,7 +73,7 @@ package test
 {
 	object MainTest
 	{
-		val Version = "test-" + xsbti.Versions.Sbt
+		val Version = "test-" + System.currentTimeMillis
 	}
 	class Exit(val code: Int) extends xsbti.Exit
 	final class MainException(message: String) extends RuntimeException(message)
diff --git a/project/build/XSbt.scala b/project/build/XSbt.scala
index 987eb09c5..9b2649349 100644
--- a/project/build/XSbt.scala
+++ b/project/build/XSbt.scala
@@ -119,11 +119,21 @@ class XSbt(info: ProjectInfo) extends ParentProject(info)
 		val ivy = "org.apache.ivy" % "ivy" % "2.0.0"
 		override def deliverProjectDependencies = Set(super.deliverProjectDependencies.toSeq : _*) - launchInterfaceSub.projectID
 	}
-	class InterfaceProject(info: ProjectInfo) extends DefaultProject(info) with ManagedBase with TestWithLog with Component with JavaProject
+	abstract class BaseInterfaceProject(info: ProjectInfo) extends DefaultProject(info) with ManagedBase with TestWithLog with Component with JavaProject
+	class InterfaceProject(info: ProjectInfo) extends BaseInterfaceProject(info)
 	{
 		override def componentID: Option[String] = Some("xsbti")
+		override def packageAction = super.packageAction dependsOn generateVersions
+		def versionPropertiesPath = mainResourcesPath / "xsbt.version.properties"
+		lazy val generateVersions = task {
+			import java.util.{Date, TimeZone}
+			val formatter = new java.text.SimpleDateFormat("yyyyMMdd'T'HHmmss")
+			formatter.setTimeZone(TimeZone.getTimeZone("GMT"))
+			val timestamp = formatter.format(new Date)
+			FileUtilities.write(versionPropertiesPath.asFile, "version=" + version + "\ntimestamp=" + timestamp, log)
+		}
 	}
-	class LaunchInterfaceProject(info: ProjectInfo) extends  InterfaceProject(info)
+	class LaunchInterfaceProject(info: ProjectInfo) extends  BaseInterfaceProject(info)
 	{
 		override def componentID = None
 	}