CLR profiler does not seem to work with the Silverlight CLR. Does another memory profiler exist?
VS2010/SL4 has a profiler now checkout:
http://www.nachmore.com/2010/profiling-silverlight-4-with-visual-studio-2010/
http://blogs.msdn.com/b/seema/archive/2010/01/28/pdc-vs2010-profiling-silverlight-4.aspx