Bill Wagner's Effective C# is one of the books you absolutely need to have living on your bookshelf if you're working in .NET. Bill's book is crucial to understanding how certain things in .NET and C# work, and it's full of great examples on why you need to do things in a particular fashion. He goes in to exactly the right level of detail to make you understand things like the as/is keywords, and why you really need to think hard about how to implement equality checking.
Effective C# covered C# 1 with just a nod to 2.0, so it's good to hear Bill's nearing completion of his work More Effective C#, updated for all the goodness of C# 2.0 and 3.0. You can pre-order through Amazon, and it's also available on Rough Cuts where you can get read the chapters as they're going through the editing process.
I'm really looking forward to getting a copy of this when the dead tree version comes out in November. (Hey, maybe a birthday present for myself!)