Don Smith from the Patterns and Practices group has published an architectural and development guideline around the Web Service Software Factory specifically for WCF.
The Web Service Software Factory (also known as the Service Factory) is an integrated collection of tools, patterns, source code and prescriptive guidance that helps our customers quickly and consistently construct Web services that adhere to well known architecture and design patterns. The Service Factory provides guidance that addresses many of the challenges associated with building WCF and ASP.NET Web services and the components of a distributed application. These challenges include:
Find it here: http://msdn.microsoft.com/servicefactory