A new book on WCF was just published by Juval Lowy at IDesign. For those of you that don’t know, Juval is Microsoft’s Regional Director for the Silicon Valley area and has helped in the internal strategic design reviews for the .NET Framework. He has presented sessions at the last two Tech·Ed conferences on WCF and helped shape the technical strategy and direction for WCF with Microsoft.
I haven’t picked up my copy yet, but will be getting one soon. The book focuses on the “why” behind particular design decisions in WCF and is a practical approach to building WCF enabled services.
There is also a new “Rough Cuts” edition of Learning WCF available by Michele Leroux Bustamante (also at IDesign). This book is aimed at the WCF beginning to intermediate programmer and focuses on the actual transmission (what happens on the wire) and interoperability techniques, while Juval’s book is aimed at more advanced developers and focuses on the system side of developing WCF applications.
In any case, both of them should be good to add to your library. I know I will be adding them to mine.