Integrating recent changes to the wiki:

commit 7ebbd8ea455bb59c7c2ef58ce706cb0c60148d22
Author: havocp <hp@pobox.com>
Date:   Sun Sep 30 14:06:21 2012 -0700

    Try to explain briefly what a command is at the top

commit 8c19257aeeb488a7121090d70698574b1041044e
Author: syrix <github.com@sbayer.eu>
Date:   Wed Sep 26 18:22:55 2012 -0700

    Replace invalid link to Knockoff

src/sphinx/Extending/Commands.rst

@@ -2,9 +2,17 @@
 Commands
 ========
 
+What is a "command"?
+====================
+
+A "command" looks similar to a task: it's a named operation that can be executed from the sbt console.
+
+However, a command's implementation takes as its parameter the entire state of the build (represented by :doc:`/Extending/Build-State`) and computes a new :doc:`/Extending/Build-State`. This means that a command can look at or modify other sbt settings, for example. Typically, you would resort to a command when you need to do something that's impossible in a regular task.
+
 Introduction
 ============
 
+
 There are three main aspects to commands:
 
 1. The syntax used by the user to invoke the command, including:

src/sphinx/Extending/Plugins.rst

@@ -8,7 +8,7 @@ Introduction
 A plugin is essentially a way to use external code in a build
 definition. A plugin can be a library used to implement a task. For
 example, you might use
-`Knockoff <http://tristanhunt.com/projects/knockoff/>`_ to write a
+`Knockoff <https://github.com/tristanjuricek/knockoff/>`_ to write a
 markdown processing task. A plugin can define a sequence of sbt Settings
 that are automatically added to all projects or that are explicitly
 declared for selected projects. For example, a plugin might add a

src/sphinx/home.rst

@@ -43,7 +43,7 @@ Getting Started
 
 To get started, *please read* the :doc:`Getting Started Guide </Getting-Started/Welcome>`.
 You will save yourself a *lot* of time if you have the right understanding of the big picture up-front.
-All documentation may be found via the `table of contents <index>`.
+All documentation may be found via the :doc:`table of contents <index>`.
 
 The mailing list is at http://groups.google.com/group/simple-build-tool/topics and should be used for discussions and questions.
 Questions may also be asked at `Stack Overflow <http://stackoverflow.com/tags/sbt>`_.