A gyroscope just resists rotation. You can measure that resistance to calculate how much rotation has happened. MotionPlus includes a multi-axis gyroscope so the orientation of the Wii remote on each axis can be tracked in terms of change from a previously known orientation, a.k.a. home position. Combine that with the existing accelerometer, and you can see a dramatic improvement in waggle-ometry, but you still won't have the mythical "exact position in space" we all thought Nintendo was talking about back in '05.