MEF live on CodePlex
The Managed Extensibility Framework (MEF) is a new library in .NET that enables greater reuse of applications and components. Using MEF, .NET applications can make the shift from being statically compiled to dynamically composed. If you are building extensible applications, extensible frameworks and application extensions, then MEF is for you.
If you want to learn yourself check out http://www.codeplex.com/MEF
If you want to hear about it from me vote for my session on Develop Academy III survey here
