Using iPad 2's front facing camera, and some software hacking magic, the Engineering Human-Computer Interaction Research group has managed to create some pretty interesting 3D effects.
TUAW has the story, and says the group is calling it "Head-Coupled Perspective." Basically the software uses the camera to track the user's head, and gives you a virtual 3D effect.
It's currently just a demo, but check out this video. This kind of thing could be a doorway to some pretty cool games and applications in the future.