I am starting getting excited about WPF/E finally there will need to deal with Flash just XAML. It runs on Windows and Mac plus IE, FireFox and Safari. I don't see Opera in the list, we'll see.
Check out Microsoft's WPF/E Referances. You can down load it from here.
Some blogs of interest Joe Stegman’s “WPF/E” tales and Mike Harsh's Blog