Wow, great idea!

I haven't tried the app yet, but if it immediately shuts off other applications when switching to a group, I think that needs to change, or at least provide a setting to just keep all the apps running but hide them from the tab switching menu some how (i know it could be a memory killer, but for my own personal use, which usually doesn't require a lot of apps running, i think it would be perfect).

Other than that, it's a great little app, put it on the AppStore for some cash :) (and add a screencast)