"It has a tri-axial accelerometer and a high-resolution, high-speed infrared camera, which can sense movement with better than 1 millimeter accuracy."
Possible uses:
- Inertial Navigation unit. No gyros, and of questionable accuracy. But take several and average the results to make up for that? Also, more than one working together could measure rotation.
- Sun-tracker. Wiimotes seem perfectly capable of this.