Cool multi-touch trick
 

I found that you can close/open multiple folders at the same time. Just tap to close with multiple fingers. You can even close a project and its enclosing folder - you'll see the project close first, then the folder will scroll shut.

This is truly a multi-touch thing, as if you mistime it slightly (quickly tap one then the other) the animation will block the second press from being registered.

Mostly pointless, but perhaps there might be cases such as wanting to collapse alot of projects quickly.