This is another post that doesn't really present brand, spanking new information.  However, there seems to be quite a few people that don't know about it. 

For those interested in learning about the details of the WCF channel model, there is a free mini-book available on the WCF community site that is a great starting place.  Although it was originally written based on the earlier bits of WCF, it continues to be an excellent resource.  The mini-book contains eight chapters that provide a detailed look at both the channel model and how to build custom channels.  It will likely be of particular interest for developers that are extending the WCF channel stack.

You can access the mini-book here: http://wcf.netfx3.com/files/folders/product_team/entry3550.aspx

Enjoy!