A while back, Jorge Castro set up a page on the Ubuntu Wiki for all the Unity keyboard shorcuts and the page was always updated once Unity gained new keyboard shortcuts. For some reason that page is no longer available and the Unity keyboard shortcuts documentation moved to AskUbuntu:
This page will document the keyboard shortcuts for Unity as they get defined. Please feel free to add more!
Note: Some of these aren't implemented yet as Unity is in Alpha, but we're putting these here to document them ahead of time.
Wherever the page is located, it's nice to have this documented - I don't know about you but I for one have always missed a keyboard shortcuts list for Compiz.
If you discover some new / undocumented Unity (for Ubuntu 11.04) keyboard shortcuts, post them @ AskUbuntu Unity Keyboard Shortcuts page.