As usual, Roman Kiss continues doing great stuffs for WCF. He has recently published a new NullTransport for WCF in CodeProject.
This transport is really useful for In-Process communication when the client and the service run on the same windows process. Before having this transport, the recommended transport for scenario was Named pipes.
Read more about this transport in the article he published here http://www.codeproject.com/WCF/NullTransportForWCF.asp