I've googled around a bit, and I haven't been able to find a good listing of what classes from the .net CLR are not included in the 'CoreCLR' aka Silverlight.
What is Silverlight missing from the Windows .net Framework?
Also, is there anything that the Silverlight runtime has that the .net Framework doesn't?
Silverlight Runtime (Silverlight CLR) is essentially a mini-mini CLR :).
Microsoft did the work of removing many dependencies to .NET Framework assemblies not part of the Silverlight release
Silverlight CLR is a subset of the
.NET Framework that contains
components and libraries, including
data integration, extensible Windows
controls, networking, base class
libraries, garbage collection, and the
common language runtime (CLR).
Some parts of the .NET Framework for
Silverlight are deployed with your
application. These "Silverlight
Libraries" are assemblies not included
in the Silverlight runtime and are
instead shipped in the Silverlight
SDK. When Silverlight Libraries are
used in your application, they are
packaged up with your application and
downloaded to the browser. These
include new UI controls, XLINQ,
Syndication (RSS/Atom), XML
serialization, and the dynamic
language runtime (DLR).
To read about a detailed comparison, see this link http://codebetter.com/blogs/patricksmacchia/archive/2008/10/01/comparing-silverlight-and-the-net-framework.aspx
You can see the online Silverlight 2 Documention which includes API documentation.
Or go to the Silverlight 2 Getting Started Page and either download the addins for Visual Studio 2008 if you have it (it works with the free Visual Web Developer Express if you don't have Visual Studio 2008) or download the Silverlight 2 SDK which is listed lower on the Getting Started page.
Once you have the Silverlight 2 SDK installed, you can launch Start -> All Programs -> Microsoft Silverlight 2 -> Welcome, which has links to the installed documentation as well as other resources.