I've found that the best way to get to understand a particular technology is play around with it. As such, when I started working on a WCF project for one of my customers I created a simple test harness that let me play about with WCF Service Contracts and WCF Data Contracts quickly and easily. Anyway, I've made my WCF test harness available here:
http://code.google.com/p/koln/
The test harness uses RhinoMocks to mock out my WCF Services and NUnit to enable a simple set of automated unit tests.