The only games available at the moment are the ones you get with the Wii - Golf, Baseball, Boxing, Tennis and Bowling.
I didn't actually play the games to finish them, I've just tried them all out to get the feel of the controller, and I must say that I'm impressed with its responsiveness. You can especially see that while playing Boxing - every movement you make is correctly registered by the Wii, and you actually have to hold your hands up to protect yourself.
I can understand why they initally wanted to call it Revolution - it definitely will revolutionize gaming as we know it. Can't wait to try out Zelda, which should be available soon.