David Chappell has written a whitepaper. As he says in his blog:

One way to appreciate the value of WCF is to take a look at the range of communication styles it supports, especially in the .NET Framework 3.5. I've written a white paper that's meant to help with this. Called Dealing with Diversity: Understanding WCF Communication Options in the .NET Framework 3.5, the paper walks through the variety of approaches that are now supported. Along with the traditional things, like Web services and queued messaging, this latest WCF release adds support for RESTful communication, RSS/ATOM, and an interesting option called the WCF Line-of-Business Adapter SDK. The paper also takes a look at how WCF is used with BizTalk Services.

The white paper can be downloaded at http://www.davidchappell.com/articles/white_papers/WCF_Diversity_v1.0.docx.