ScottGu gives a First Look at Silverlight 2.
Though not directly related it's likely worth also to mention the experimental Volta project that turns .NET MSIL code to JavaScript.
Since .NET advent and its attempt to uniy Windows and Web developement on a single consistent platform, WPF now brings a markup language to create Windows UI, Silverlight brings a subset of .NET and WPF into the browser and Volta allows to create JavaScript code from .NET based code.