Ubuntu Unity 11.04 is out for everyone now.
The Unity interface is a huge overhaul and has a ton of new features and keyboard shortcuts. If you are a power user or want to be one, knowing keyboard shortcuts (or atleast having them close by) is a surefire way to that.
AskUbuntu has created a nice wallpaper with the Ubuntu Unity keyboard shortcuts.
You can download the wall paper that has an overlay of all the keyboard shortcuts over the default Ubuntu wallpaper.