Prism 4.0 and MEFhttp://blogs.msdn.com/b/blaine/archive/2009/12/20/prism-4-0-and-mef.aspxDavid Hill has a recent blog post that discusses how Prism 4.0 (Composite Application Guidance for WPF and Silverlight) and MEF will work together. You might be thinking what happened to Prism 3.0. We decided to call the next version of Prism to be 4en-USTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)