Dustin Metzgar recently posted an entry which describes an interesting performance scenario in WCF.  He used a couple of different tools to examine the problem, including the Concurrency Visualizer.  See his entry here: http://blogs.msdn.com/b/dmetzgar/archive/2011/05/04/wcf-scales-up-slowly-with-bursts-of-work.aspx.

James Rapp - Parallel Computing Platform