Some sources from MTV Networks indicate that Microsoft is working on a Wiimote Controller specially designed for X-Box 360. Also able to receive signals from a LED sensor bar (like the Wii), but one-ups the Wiimote due to its microphone on board for Xbox Live chat.

 Not many aspects are known yet except its colors and that it will use the standard rechargeable battery. Lauch date might be somewhere at the end of 2008.

Wiimote-Style Controller for X-Box 360: [Via]