I got back from Mix last week and what a good time it was! I couldn't see all the talks I wanted but have been watching them over on the Mix site: http://sessions.visitmix.com/
Some of my favorites were:
If you just want a good overview of Silverlight checkout the keynote with ScottGu!
On a side note they had some xbox 360's to play with during the conference and Guitar Hero II, so after trying it out there I came back and picked one up. The cool thing is my wife is enjoying it as well, so that means I get more time on it! :-)