"Using the infrared camera in the Wii remote and a head mounted sensor bar (two IR LEDs), you can accurately track the location of your head and render view dependent images on the screen. This effectively transforms your display into a portal to a virtual environment. The display properly reacts to head and body movement as if it were a real window creating a realistic illusion of depth and space." - (Taken from Youtube)

I think this looks prety cool, can't wait to see something like this used in games in the near future.
It's also pretty cheap to make if you have a Wii + a computer already.

Here's the video link http://www.youtube.com/watch?v=Jd3-eiid-Uw