Don't agree with some points
>Silverlight is late to the game.
No! Silverlight isn't yet another Flash. Flash was made for multimedia, while the Silverlight market is rich Internet applications.
>The design tools are Expression Blend and Expression Design
>- but who uses them? The design world uses Adobe PhotoShop.
Once again. Silverlight is not for fancy graphics, it is for rich user experience.
>Silverlight is a browser-only solution
Yes, but have you ever heard about WPF? Silverlight its younger browser. WPF uses XAML as well, so it won't take much time to port your web app to desktop and vice versa.