Another feature that I would like, is the ability to play the FM tuner in any room. I've been replacing most of my normal stereos with network based media extenders and PCs. Having a network based FM service will come in handy. (many times you just want to listen to local news and music!)
I've just started jumping into the MCE experience. In many ways I believe it to be a better alternative to the OpenSource MythTV and the like. Mostly because the content providers will be behind a company like Microsoft.
Anyways, here are some links that I've been reading so far:
Extender resource - info on extenders.
The Green Button - site all about MCE
Windows Media Center Sandbox
To program windows media center you can use a markup language called MCML - media center markup language. There is also a Windows Media Center SDK available from the team blog which gives you templates and code samples for accomplishing a MCE app.