The Wii-mote has the camera inside the device and the markers on the TV, plus 3 accelerometers.
“Sony applied to the United States Patent Office (USPTO) for a patent on a “hand-held controller having detectable elements for tracking purposes.”
From the patent application :
Because this data is gathered on an image frame-by-frame basis, the data can be used to calculate many physical aspects of the movement of the controller 110, such as for example its acceleration and velocity along any axis, its tilt, pitch, yaw, roll, as well as any telemetry points of the controller 110.
The controller uses four LEDs to capture this motion, but in a twist from Nintendo’s sensor bar configuration, the LEDs are mounted on the controller itself. A camera mounted next to the player’s television set takes many pictures of the four LEDs every second, and this data is used to calculate the position and velocity of the controller.
Will Microsoft retaliate with a motion-sensitive controller of its own?