Just to rub it in Nintendo's face a bit more, during the demonstration at E3, the guy explaining the system said "This isn't a game where you end up on the sofa just kind of using some preset waggle commands."
Ow.
Ow.
This thing is going to absolutely destroy the Wii, if it works as advertised...
This is quite bad at gestures though, particularly when the front of the Wiimote is pointed away from the sensor bar (as it is in games like boxing and tennis). In these cases, lacking a visual way to tell movement, the controller relies entirely on the accelerometer, which while theoretically capable, saturate very quickly with full body motion.
This is why in Raving Rabbids, where you have to play rabbid-DDR with the music, you have to jerk the controller - the accelerometer is neither reliable nor accurate enough to reliably infer your intentions through light motions.