MEF's design supports lazy loading, however it does not include a lazily loaded catalog.

This catalog would use ReflectionModelServices to write to an xml/text file the catalog contents. It would then lazily load the assemblies in the catalog as needed.

This catalog would create parts in separate appdomain and return proxies. If something goes wrong in any part, the application won't crash since the parts would be separated from the core app.

These are great features in Silverlight and missing on the desktop version.

I'm interested in helping.