8bitjoystick (a site known for some good Xbox 360 intel) has confirmed that Microsoft has been working on an Xbox 360 accessory known as "lips." What's "lips," you ask? No one knows for sure, though we know it's not the Wiimotesque Newton, and voice certainly comes to mind.
8b: "I can confirm the existence of a new Xbox accessory codenamed : Lips
A couple months ago I got a hold of a treasure trove of information straight from the internal working of the engineering team at Xbox. I learned a heck of a lot what was really going on with the Red Ring of Death, New Xbox 360 motherboard designs and I learned about three accessories that they are working on."