Is there any documentation for Unity 2D? The only settings available seem to be buried in gconf and are a bit cryptic.
Mariano Chavero has made "A simple GUI for Unity-2D Settings": http://marianochavero.wordpress.com/2011/04/20/a-simple-gui-for-unity-2d-settings-ubuntu-11-04/ This may not answer your question but might help decrypting the options in gconf-editor.
According to the Wiki page for Unity2D it's architecture is very close to Unity and shares all the same backend components so the documentation for Unity would be relative.
The Unity2D version's only difference is it uses Qt/QML for the UI portion while utilizing the existing Unity core components for indicators, places etc.
Having said all that there is currently no documentation for Unity and is filed as a bug report.
There is a useful list of keyboard and mouse shortcuts here Unity keyboard/mouse shortcuts