<p>CLR profiler does not seem to work with the Silverlight CLR. Does another memory profiler exist?</p>

Doesn't seem to be one available yet. However, as
recommended in this forum thread
, you can convert your Silverlight app to a WPF application and profile that:
There is no tool as of now but as a workaround you can easily create a desktop (WPF) version of your Silverlight client from the same code base and few tweaks (refer Scot's blog for an example on this -
http://weblogs.asp.net/scottgu/pages/silverlight-tutorial-part-8-creating-a-digg-desktop-application-using-wpf.aspx
) .  Once you are done with this you can run any performance profiler that works with WPF.
Not an optimal solution, but it sounds like the best option for now...
Update:
Just saw a
blog post
about XPerf which is a cpu sampler for Silverlight. Not exactly a memory profiler but a good tool for testing the performance of Silverlight apps...