The architecture for this would be interesting and, no, it wouldn't be simply dropping in existing games. You would have to re-tailor a program to work here because, as I stated in other threads, you cannot instantiate multiple copies of the XNA Game class. It simply doesn't work. Therefore your application suite program would have to support a nice modular API that other applications (or games) can be built using.
It probably wouldn't be terribly hard for it as long as you set down some concrete rules and things. For instance you have to choose whether the mini OS will unload its content before launching a game/app. That determines what new memory restrictions are placed on the game/app. Maybe a few others.
All in all I think with some smart architecture this wouldn't be completely out of reach. Again the biggest issue here is that you won't just be able to add the existing games/apps to this; you would have to rewrite them in the context of this application. Either way, good luck with this one Tiptup.
Edit: I do have an interesting idea on how you can deploy new games to this system without redeploying the whole suite. I'll try a prototype tonight and let you know how it goes, Tiptup.