Stumbled on this today (thanks NewsRoom!). Really quite a nice little UI add on.
Now when I single press home screen it takes me to home, long press it brings up recent apps, but double click and I now get the Power Strip UI appear - over the top of any app/place I happen to be in the phone. Does quite a few nifty things, task switching for one, even opens widgets from within Power Strip, lets you context-menu the apps for doing a bunch of stuff like sharing their market links to FB/Twitter/Email/Bluetooth/Messaging etc, uninstalling, force closing...
Blogs: androidnz.net, blog.clove.co.uk