A lecture on API design by Krzysztof Cwalina (the brains behind the Framewok Design Guidelines) has been posted on the Research Channel.

This class presents best practices for designing frameworks that are reusable object-oriented libraries. The guidelines are applicable to frameworks ranging in size and in their scale of reuse from large system frameworks to small components shared among several applications. They started as a small set of naming and design conventions, but have been enhanced, scrutinized, and refined to a point where they are generally considered the canonical way to design frameworks at Microsoft. They carry the experience and cumulative wisdom of thousands of developer hours, over three versions of the .NET Framework.

I've seen Krzysztof (and Brad) present this personally and it is definitely worth seeing. Set some time aside this weekend to watch this and enjoy.