TwitterMCE puts twitter in you Media Center. With the new TwitterMCE app you can post tweets, view friends, followers and timelines within Media Center.
The beta program is a MCML program and works on: Microsoft Windows Vista Premium, Microsoft Windows Vista Ultimate or Microsoft Windows 7 Media Center.
You'll probably want a decent MediaCenter keyboard if you do much "tweeting" from MediaCenter, but the app looks nice and worth a try for all of you twitter addicts.
Read more about TwitterMCE at the GreenButton forums and download it from MCEZone