Cheryl from the Silverlight SDK team will give you some pointers on how to decipher whether you are in the .NET Framework for Silverlight or the full framework docs and how you can navigate between the two documentation sets.
We can tell based on some of the feedback we've received, that folks are landing in the wrong documentation set and don't realize it. The .NET Framework for Silverlight often looks and smells like the full .NET Framework, but it's smaller, and in some cases the same API behave differently. We are investigating different methods for fixing the wrong doc-set problem.