I've already done lots of reading on the C# programming language, so I must admit that I mostly skimmed The C# Programming Language, by Anders Hejlsberg et al. This book is quite easy to read, and it has anything you'd ever want to know about C#, so if you're writing serious C# code, you'd certainly benefit from having this book available.
Part I is about C# 1.0, and I mainly skimmed the table of contents here. One section that caught my eye was “Atomicity of Variable References,” in which I read that simple reads and writes of integral types of 32 bits or less are guaranteed to be atomic. That's good to know; I'd hate to use a lock around a simple integer if I didn't have to.
Part II is about the eagerly anticipated C# 2.0, and I enjoyed reading about it. I'm greatly looking forward to generics, anonymous methods, and iterators, and enjoyed reading the fine details. It looks like they did a thorough job, and I think the new features will make C# a far better language. Whether it will be good enough to keep me away from C++ remains to be seen...