Three days ago (being more specific, on Friday 13th ;) ) I've passed my first Microsoft developer's exam, 70-536 TS: Microsoft .NET Framework - Application Development Foundation, scoring 876 points out of 1000. In short, I had 40 question and 135 minutes. As far as questions are concerned, there were many about serialization (rather not very straightforward), interoperability and globalization. No questions about mailing functionality. The questions ranged from very simple to quite though. Most of them were single choice questions, I got maybe three or four multiple choice ones.
Some say this is an easy exam. Well, I wouldn't say so, because the exam covers almost every .NET basic subject. In order to pass, you need to have solid theoretical background, but at the same time you need to get you hands dirty by playing with some code samples too. I recommend examining the official Training Kit (now there's 2nd edition, the first one was quite buggy so don't rely only on that book). Skimming MSDN seems like a good idea too ;) However, there's no better source of knowledge than the developer's head and experience. Most of the questions I answered because of my experience and not because of the books!
Next, I'm going for the exam 70-502: Microsoft® .NET Framework 3.5—Windows® Presentation Foundation. Good luck with your own certifications!