WPF\E
WPF\E was a cool session to see at Mix, ok I wanted to see more but it was dam cool to see WPF apps working as browser plugins on IE and FF. I have said it all before, largely about Flex and what it means to .NET developers that I am quite frankly done saying it. What happens now is up to them but Microsoft are at the party, I think Jesse sums it up better than me.
So, basically, if I was working for Adobe/Macromedia, I would be pissing my pants right now. Microsoft has a tendancy to take good ideas and do them right.