Yesterday, I've successfully completed my first developer's certification by passing exam 70-502 TS: Microsoft .NET Framework 3.5 – Windows Presentation Foundation Application Development. My score was 921 out of 1000 which is also my personal best so far :)
I had 51 question, most of which were single choice, and 150 minutes to complete. Not all the questions were taken into account when computing the final score. Although I've chosen my questions in C#, I got one question in VB, so be prepared ;)
What can you expect from the exam as far as questions are concerned? Putting it simple, everything. Questions cover all the WPF' topics including WPF 3D, ClickOnce deployment, XPS and Flow documents, and Windows Forms interoperability.
As far as WPF 3D is concerned, the questions are rather easy and cover only the basics like cameras or meshes. If you are a novice, I recommend a brief reading about this subject (not because this appears on the exam, but because WPF 3D is a big fun). ClickOnce was heavily covered on the exam, so make sure you get your hands dirty playing with it. Besides basic knowledge, you should know how to download parts of the application on demand (parts which are not required for the application to run). Regarding flow documents, you should know what annotations are, how to manage them, display, persist, etc. Printing both flow and XPS documents is also covered on the exam, so brush up on this subject as well.
In my last words, I want to speak a little about books :) Generally, if you're already familiar with WPF, official Training Kit from MS is mostly sufficient, but it doesn't cover WPF 3D, and some subjects are touched rather briefly. But if you are at the very beginning, or if you simply want to broader you knowledge, I highly recommend picking up Adam Nathan's WPF Unleashed. Actually, if You are serious about WPF development, this book is a must read :)
Wish You good luck!