I've been waiting for this one! The public version of the .NET 2.0 source code has been released! Otherwise known as the SSCLI 2.0 (Shared Source Common Language Infrastructure 2.0), this is basically the .NET 2.0 framework source code (among other things). With Reflector you can view the framework code, but this is the original code before any compilation thus leaving the developer comments in tact. It's also a bit cleaner here.
Not only that, but you get a load of unmanaged code. I'm talking about real hardcore CLR stuff. It also includes the C# compiler source code as well as the code for ILASM, ILDASM, and a bunch of other utilities. It's going to be really awesome seeing how generics and anonymous delegates are implemented.
My favorite piece that came with SSCLI 1.X is still here: there C# code for the JScript compiler (yes, the JScript compiler is written in C#). I actually used the original source code for the basis for a brain bender quiz in my .NET class. I highly, highly recommend the use of this SSCLI for your educational endeavors. Either to help you learn more, or to help others out.
Here's the link to download the SSCLI 2.0: