Possible Duplicate:
Choosing between MEF and MAF (System.AddIn)
Is the Managed Extensibility Framework a replacement for System.Addin? Or are they complementary?
Possible Duplicate:
Choosing between MEF and MAF (System.AddIn)
Is the Managed Extensibility Framework a replacement for System.Addin? Or are they complementary?
Short answer no it is not. System.Addin allows you to isolate add-ins in to a seprate app-domain / process. It also provides facilities for versioning. These capabilities are critical for many customers particularly large ISVs. MEF on the other hand is designed to be simple programming model for extensibility. The two can work together and complement each other.
It is touched in the MSDN Forums here:
Comparison to the AddIn libraries?
And also by Krzysztof Cwalina in his blog on the release of MEF:
Managed Extensibility Framework
Summary: they live side by side.
.. just two links for further reference: