I'll have a bunch more to say about it, of course, but first off let me just provide links to the important stuff relating to the media side of things.
Scott Guthrie's always-excellent blog post roundup:
Technical overview of media features:
Expression Encoder 3 overview:
Extensive blog post about Expression Encoder 3 new features (it is awesome):
Alas, the RC of that isn't available for download quite yet. Soon, I'm told.
And I had this interview on Streaming Media about the new media features: