As mentioned on 360 updates, runtime 360 has released a transcoder for media center that is oriented to streaming divx (or any currently unsupported media) from a Media Center Edition PC to an Xbox 360.
As described on runtime's site:
"Designed for Windows XP Media Center Edition 2005 and the Xbox 360, Transcode 360 aims to broaden the support for a wide range of video media including DivX and XviD." ... "The solution transcodes video files into Windows Media Video which is supported by the Xbox 360. As a first iteration, author Casey Chesnut has done a great job in turning over a working solution. There are of course several things that could be improved from the usability perspective. Thats where Transcode 360 steps in. I've taken the same concepts and written a solution from the ground up with the purpose of making video playback more robust and accessible."
It's interesting to see a media playback community developing around the Media Center / 360 extender functionality. Even if these guys are writing work arounds for the MCE technology so they can stream their already encoded or downloaded (such as movie trailers) content, the 360 is bringing the wired home to an audience that seems broader than early adoping media enthusiasts who have traditionally been our customers with Media Center.