As reported on Gamasutra, Nintendo showed off some of the cool new Wii features in Zelda: Twilight Princess, among other games. One very cool one: you can use the motion-detecting controller to pull back an arrow on your bow, and while you're doing that, a speaker built in to the controller plays the sound of a bow being pulled, so it sounds like you're actually doing it. Cool!
And the game also has motion-detection-based nunchucks. And you can never really have enough nunchucks - let's face it. I would play Tetris more often if it had nunchucks in it.
Less interesting? Pokemon Mystery Dungeon.
Anyway, the Wii should definitely be a unique platform - great moves by Nintendo!