MEF has now been released, a Plug-In Framework, for .Net 4.0
After reading up on CodePlex, I have generated a small application that provides a plug-in framework, see attached below.
MEF.zip (70.88 kb)
I've also produced a .NET 3.5 version too:
MEF in 3.5.zip (427.41 kb)
Few MEF links:
MEF on CodePlex
Channel 9 Silverlight 4 MEF Screencasts