The NY Times has a dedicated gaming ninja, Seth Schiesel, on the floor at E3 and he has some hands-on time with the Wii. The verdict? Gyroscopic controllers are cool and that this thing might actually be worth buying.
First up was a tennis game. This was certainly the simplest game because I didn't have to press any of the controller's buttons at all. It was set up as a doubles match with a split screen, and simply swinging the controller in a tennis-like motion caused both of my players (the one at the net and the one back on the baseline) to swing simultaneously, sort of like a pinball machine where one button causes two flippers to flip, one at the bottom and one at the top.
Hands-On Time With Wii From Nintendo [NYTimes]