What .NET functionality does Server Core on Windows Server 2008 R2 not support?

As you may know, Server Core installations of Windows Server 2008 R2 now support the .NET framework.

But, some functions are not available on Server Core. As Server Core only has a command prompt and no GUI, mostly Graphical User Interface objects are not supported.

For a list of the .NET 2.0 features, excluded see here
Additionally for .NET 3.0/3.5 see here

Also remember that installing products like SQL Server 2005/2008/2008 R2, Exchange Server 2003/2007 , SharePoint Server 2003/2007 and others are not supported on Server Core. If a Server product supports Server Core installations, it will be clearly documented. If nothing is said, you need to assume it is not supported.