The Playstation Move controller is a pretty nice idea. You have an accelerometer/gyroscope system in your hand, which also has a glowing ball attached. The glowing ball is tracked by a camera at your screen and the combination of the systems gives you a pretty decent and accurate tracking system for a single position and angle in 3D space. It's close to a 6 DOF (degrees of freedom) system.
A lot of the demos and games that are out so far are basically technology demos . . . minigame compilations that make a bit of use of the motion controls.
However, I've installed the patch for my copy of Heavy Rain and played that a little with the move controller. I can say without a doubt that it's vastly improved compared to the old controller version of the game . . . instead of feeling like you're pressing an arbitrary button (and also sometimes having to think twice about which button is which in order to make something happen) you make movements that are reasonably correct in relation to what's happening in the scene. I'm looking forward to sitting down and actually playing this game through now.