The (Framework Design Guidelines : Conventions, Idioms, and Patterns for Reusable .NET Libraries (Microsoft Net Development Series) is a book written by Ms-Insiders who are involved with designing .NET 1.0,1.1, 2.0 and Vista.
The excellent thing about this book is not the guidelines (Do and Don't) but also the side-notes commentories by some industry gurus.
The new thing about the book is the focus on building a Devoloper-Freindly framework.
All in all, I do find that my code is better or more accessable to the rest of the team as a result of implementing dome of the book's guidelines...