Brian Noyes, who is an awesome speaker on .NET, is doing a low cost one day class called Essential .NET in Reston on Feb 3rd. The morning is a drill down on the C# language. The afternoon session focuses on details of the way the CLR manages assemblies and memory in the .NET framework.
For more info or to register, go here.
I've personally learned a lot about .NET by listening to Brian, and I expect to get a lot out of this class!