According to an Examiner report, a recent Microsoft presentation has indicated that the company will be releasing an application called "Smart Glass". That report is backed up by Engadget, who say they saw a similar presentation.
"Smart Glass" will allow AirPlay-style content sharing between mobile devices and Xbox 360s, including allowing tablets and phones to send content to the 360 for playback on a TV. Interestingly, the app is said to support Windows, Windows Phone, Android and iOS, meaning that owners of Apple's ubiquitous iPhones and iPads will be able to stream content from those devices straight to their Xbox 360s. So, Smart Glass will act like a media player that allows users to take the movies and music on their mobile devices and stream them directly to their TVs or home entertainment systems.
So, still just a rumour, but enough people are indicating its veracity that it seems for real. Sounds like we'll learn more about Smart Glass at E3.