We don't currently have any plans for Silverlight compatibility/port of the MGraph OM, but if that's an important scenario for you, I encourage you to log a feature request on our connect site: https://connect.microsoft.com/oslo
Well, there is a web implementation of "M" made by Mathew Willson: http://jsmeta.googlecode.com/svn/trunk/bin/JSMetaPad.html Since it is pure cross-browser javascript, you could quite easily use this in silverlight.
But sofar there is no Quadrant-workalike, allthough Mathew plans to build one.
We don't currently have any plans for Silverlight compatibility/port of the MGraph OM, but if that's an important scenario for you, I encourage you to log a feature request on our connect site: https://connect.microsoft.com/oslo