I've noticed one thing about MIX attendees so far, particularly related to Silverlight.  They are FLOCKING to presentations about it.  The keynote this morning from Scott Guthrie was really a galvanising call to action, 1.5+ million downloads A DAY of Silverlight, some incredible demonstrations of the forthcoming Olympics video streaming service, Aston Martin's showroom applications (WPF and Silverlight).  Couple that with running it on mobile devices....this is going to be good, really really good.