While writing a new article, I have noticed that these two articles required some updating.

Since this article was written, a new GAC location has appeared with .NET Framework 4.0 (in C:WindowsMicrosoft.NETassembly), that furthermore doesn’t have a shell extension:

HOWTO: Reference a Visual Studio assembly in the GAC from an add-in
http://www.mztools.com/articles/2007/MZ2007012.aspx

And I have added C# sample code to this other one:

HOWTO: Get a Visual Studio service from an add-in
http://www.mztools.com/articles/2007/MZ2007015.aspx