At this stage in the game, Nintendo has officially revealed relatively little about the specifics behind the upcoming Wii U and its controller technology.
Apart from the standard features one would come to expect from any brand of console controller, we know the Wii U's will also sport a 6.2-inch touch screen with a 16:9 aspect ratio, two analogue Circle Pads, built-in accelerometer and gyroscope sensors, rumble feature, camera, microphone, stereo speakers and a sensor strip. All of that technological goodness is sufficiently impressive as it is, but a recently published patent from Nintendo revealed a little bit more about the controller many of us will be holding in our hands when the Wii U launches next year.
One of the patent's accompanying images depicts the major components of the Wii U controller including a magnetic sensor. This magnetic sensor detects the azimuthal direction which relates to the angular measurement between an observer position and a point of interest. This feature seems to be related to the part of the Wii U promotional video that was shown at E3 2011, where the Wii U controller was placed on the floor facing upwards and the user held a Wii Remote like a golf club, swinging at a ball which was displayed on the controller's screen. The observation point in this case is the Wii U controller and the point of interest is the Wii Remote. Logically, as the Wii U controller tracks the altitude of the Wii Remote and its angle of entry as it swings across, the speed and direction that the ball will travel in can then be calculated.
[Edit] Or it could be the method in which the Wii U controller keeps itself calibrated by using the Earth's magnetic field.
The patent also mentioned that the Wii U controller will feature built-in flash memory and an infrared module.