Variety claims Sony is planning to release a Wiimote-like motion sensing controller for the PlayStation 3 at the E3 expo in June:
Rumors that Sony will come out with a motion sensing device have abounded for over two years, ever since a patent was first reported on in January of 2007.
A good source saw a working prototype several months ago that largely fit what was in the patent. Sony's controller apparently used LEDs (light emitting diodes, essentially little electric light sources) and a small webcam to track the device's movements. Because the camera can read different color lights and the shape and angle of each light, it's much more accurate than the Wii-mote. It can track precise movements, including along the Z axis (pushing toward and away from the TV; something the Wii is really bad at) as well as velocity.