One of confusing message around .Net framework is about Addins, especially combined with compatibility.

What is the best way to write an addin? How to enable the compatibility of the addin with different version of .Net framework? How does addin interact with the host application?

Those questions are well known problems. They are not addressed in .Net framework 2.0, but they are certainly not forgetten. In fact, CLR formed an Add-in team, specifically to solve the issue.

Today, they see the first light of their public life.

Introducing "The CLR Add-in Team blog"

http://blogs.msdn.com/clraddins/