Today I received my copy of the Annotated C# Standard that Jon Jagger, Nigel Perry and Peter Sestoft put together.
This book is an annotated version of the C# specification that comes with plenty of comments and contributions from people that have implemented the language (It has contributions from Mono's Marek Safar, Martin Baulig, Paolo Molaro, Raja Harinath and myself, but also from the C# team at Microsoft, contributors to ECMA and some universities that researched C#).
Peter has written a number of books (Java Precisely, C# Precisely) and is also behind the implementation of C5 a Generic Collection Library (this was a great test case for Mono's C# compiler: it was quite a challenge).
Congratulations to Jon, Nigel and Peter. They have been working on this project for a long time.