Is the source code for Silverlight 4 controls available?

I can only find the sources for Silverlight 2: http:开发者_如何转开发//www.microsoft.com/downloads/en/details.aspx?FamilyID=EB83ED4C-AC85-4DE9-8395-285628EE2254&displaylang=en

Hasn't Microsoft released the source code since then?

You can always use the free .NET Reflector tool to look at the disassembled source code of any .NET or Silverlight assembly.

Also you can download the sources for the Silverlight Toolkit that additionally contains the source code for the SDK controls like the DataGrid.