This looks very cool:
I think it would be more useful for a multi-touch desktop where we don't want to actually touch the screen. If they find a way to make it work well in a mobile setting (phone in one hand, gestures with the other), it will also be really cool for phones.
+1 to the list of cool tech MS has come out with. Need to keep a running list of new and innovative things like this to hand to folks the next time they say MS only copies other people's work :)