This is just a super cool concept developed by a Carnegie Mellon graduate. He plopped it on YouTube and 6 million hits later is getting job offers from some top tech companies.

Basically this guy has hacked the motion detectors in the Wii system to display virtual spaces that react to your position to the screen. It sounds pretty unassuming until you actually see it demonstrated, which happens about 2:30 into the video. Be sure to watch the whole thing though, because it is really cool how he rigs the Wiimote and motion sensor.