gyroscopes are not defeated by small vibrations, even if they're constant vibrations. they're used in such applications as ballistic missiles, segways, the ibot wheelchair, the big dog robot thing, and many other vibration/shock intensive applications (eg, military).

i'm aware that the wii controller uses infrared, but is that the only thing it uses? i was under the impression that it also has built in gyros, and that the infrared strip was used to calculate absolute positioning when necessary, like in an FPS.