Looks like Mix08 is the place to hear about Silverlight 2.0.
From Tim Sneath's blog:
So how can you find out more about Silverlight 2.0? Well, it so happens that MIX08 registration has just opened. We're going to blast open the doors about Silverlight and a bunch of other new web products at this conference. Last year we sold out far earlier than most people were expecting. Don't miss out this year - now is the time to get signed up!