I noticed Andrew Stopford posted a great blog entry about what books are out there for learning the in's and out's of the CLR. Another resource you may want to consider, is the CLR source code itself - Rotor! What better way to understand the nuts and bolts than to dig in under the hood and make sense out of all the high level goop.
You'll find that nearly all of the runtime code follows and complies with the Common Language Infrastructure standard, and the kicker - it was built from a source branch of the real CLR! There are only a few major deviations: a different JIT, a different Garbage Collector, and the removal of COM interop support (therefore removing Winforms and ASP.NET etc). A quick PPT overview (Jason Whittington) of what's in and what's out can be found at: http://staff.develop.com/jasonw/tools_rotor_2002.ppt.
Would a post on the Whidbey CLR and Rotor Whidbey build process be interesting to you guys?