Friends don’t let friends do point to point. Anyone who has designed services to solve a business problem or built a distributed 
composite application using service-oriented techniques has, consciously or not, discovered the hazards of client applications knowing too much about all of the services with which they interact.
In my latest article for CODE Magazine, I provide a scenario-driven approach to introducing the Routing Service in WCF 4.0 including discussions on the following messaging patterns that help enable more flexible composite application designs:
Virtual Endpoint/Message Broker
High Availability
Content-Based Routing
Context-Based Routing
Publish-Subscribe
The article is now available online at CODE Magazine http://www.code-magazine.com/Article.aspx?quickid=1009051 as well as at news stands including Barnes and Noble.
I hope you like it and as always, I welcome your feedback!