The C# team posts answers to common questions and describes new language features
There are two versions of the C# specification - one from Microsoft, and one from ECMA. They are the same in all important respects (a few pieces of explanatory wording are different, but nothing that affects the specification itself) but the numbering of sections is different.
The ECMA specification is available as a PDF, or you can email ECMA and they will send you a hard copy for free. Details are on the ECMA website. Alternatively, Jon Jagger's HTML version is available and is a useful download. It is from a draft version, but it's very close to the final version. I don't know whether or not Jon Jagger is planning to make an HTML copy of version 2 of the specification when it's released.