I recall a few years ago (may be 5 or 6) from an MVP summit, the idea behind XAML and .NET 3.0 and later versions were to create a single application development framework for both Windows and Web. In other words, once I know how to use XAML tags in WPF, theoretically the same tags/code should work in a browser application without any changes. That was the idea behind WPF and WPF/e (Former name of Silverlight).
Presently, I am working with both WPF and Silverlight 2.0 and more and more I compare, not too many things match actually. Controls in WPF and Silverlight look similar but actually there are not.
Here we are again – Windows Forms and ASP.NET. Now to build a complete Web Application in Silverlight, I have to use ASP.NET, XAML, Silverlight and still may not be able to do what I have been doing in ASP.NET 2.0.
Not only that, there are so many properties and methods you will see in WPF controls but they are totally missing in Silverlight controls.
As always, Microsoft has a tendency to spend lot of money and get everybody excited about new technologies and how it will make our lives easier but more and more you get into it, more and more mess you find.
Now, Microsoft will come up with several patches (in other words, dirty fixes on top of what they already have) to slow things down and ask developers to buy more RAM, bandwidth and HDD spaces.
Just another big mess.