I had some free time today and did this:
I'd like to note that LukeH made the core raytracing engine in C#. He built it using linq and the code looks very elegant .
I did the "Silverlight" part of it. There are some things to think about with ray tracing in Silvelright - see the links at the bottom for more info.
How to Build?
Official Silverlight Raytracing Page