you kid, but I used to work for a db/information management company that was retarded enough to do this.

If it can track 48/49 joints then it's not hard to conceive of using finger gestures instead of buttons. eg. touching your first finger to your thumb to walk, or opening a closed fist while making a throwing motion in order to trigger the game to release a ball. I guess whether this would be accurate enough depends on how good Natal is, but it's certainly not hard to think up alternatives to button presses.