Back in Jun04, I was up at Microsoft for work participating in a security conference.  One of the tours that was setup for us, was of the Innovation Center and while waiting for the tour to start, I spent about 15 minutes with hands-on a Windows XP Media Edition 2003 system. 

I was impressed mostly with the ease-of-use of the GUI, and I think it could actually have some play in the "senior decision maker" space of enterprise computing (probably not in their model though).

Anyway … it seems like the 2005 version is gaining some "Big-Mo" (aka momentum):

• Costco’s most recent members magazine had a write-up about it.
• Google Search on "media center edition 2005"
• Hardware Analysis just posted "Getting started with Media Center Edition 2005"
• You can now buy the software via OEMs for build-it yourself folks
• Available via MSDN and TechNet subscriptions