Juval Lowy has an interesting article over on MSDN about building a queued WCF response.
“Windows Communication Foundation (WCF) enables disconnected work between clients and services. The client posts messages to a queue and the service processes them later. Such interaction permits a different programming model from the default request/response pattern, enabling possibilities such as load leveling, improved availability, and compensating work, to name just a few. This column starts with a brief introduction to Windows® Communication Foundation queued calls and then presents an interesting problem-how to get results out of a queued call-and the solution via some cool Windows Communication Foundation programming techniques and a few helper classes I wrote for this purpose.”