On Friday I passed the “70-503 – TS: Microsoft .NET Framework 3.5 – Windows Communication Foundation Application Development”, so that makes me a “Technology Specialist” in WCF. This is the third technology specialist (TS) exam I have taken, the others being BizTalk Server 2004, and BizTalk Server 2006, so it felt good to broaden the spectrum a bit. I prefer the TS exams to the regular .net exams; I have the MCSD certification, which required passing four .net exams and a server product exam (I chose SQL Server 2000 for that). The TS exams are much more focussed instead of covering a broad area, and the questions tend to be tougher, but more focussed towards hands-on experience.
If you are thinking of going for the exam, make sure you really know the topics that are listed in the official preparation guide here. The best book that I found for covering the basics was “Learning WCF: A Hands-on Guide” by Michele Leroux Bustamante. This will cover most of the stuff you need for the exam, and go into sufficient depth on all the topics covered, there’s also about 20 or so labs that you should run through to get the hands-on experience. If you are fully knowledgeable with everything covered here you are well on your way to pass. There are some points on the official preparation guide that are not covered in Learning WCF, so you should make sure you have the 3.5 features covered and look at consuming non WCF services.