I went to a presentation on the Managed Extensibility Framework (MEF) at the Microsoft Research Labs in Cambridge on Tuesday.
Here is the blurb:
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.
One interesting aspect is that although it is a Microsoft project and will be available in version 4 of the.NET Framework, it is currently open source!
The code is available here:
The technology itself fits in well with Model-View-Controller and Inversion of Control.
The presentation is available here:
If you want to find out more, this is a good introduction: