MEF Links

Building Composable Apps in .NET 4 with the Managed Extensibility Framework
http://msdn.microsoft.com/en-us/magazine/ee291628.aspx

Codeplex docs
http://mef.codeplex.com/documentation

Digging a bit deeper
http://www.codeproject.com/KB/library/mefpart1.aspx
http://www.codeproject.com/KB/library/mefpart2.aspx

Web casts on everything you wanted to know about using MEF in Silverlight 4
http://codebetter.com/blogs/glenn.block/archive/2010/02/16/learning-about-mef-in-sl4-from-mike-taulty.aspx

People
http://blogs.msdn.com/gblock/default.aspx