I don't pretend to know what I'm talking about, but from what I know of the Wii controller it CAN sense 3D position by interpretting data from from multiple sensors. It'd be tough to program, I'm sure, but if the controller is calibrated in a certain position, every time it is moved, tilited, or turned in any direction either the sensor or accellerometers will pick up the speed, length of time, and direction travelled, and therefore can calculate the distance travelled in any direction. If it knows the distance and direction travelled from the calibration point, it knows exactly where the controller is in 3D space.
MAYBE