Charles from Channel 9 stopped by my office a couple of weeks ago to chat with Erika Parsons and I about the ThreadPool work we're doing for .NET 4.  I learned something from this: understanding something, and explaining it in person, for the first time, in front of a camera, are two very different things. :)  If you'd like to hear a little more about the .NET 4 ThreadPool, and have about 45 minutes to spare, check out the video.  Then be sure to read a correct explaination of the A-B-A problem.