Off all the questions that i got asked, one of the most common is "which edition of Visual studio do I need to take advantage of feature X". It is usually a though question because the number VS of features is huge and the number of editions isn't also very small. :-)

If I can't answer the question directly from top of my head I tend to consult the Visual Studio Features Comparison list.

Is is so huge that there isn't a single matrix that conveys all information, but it is split among 24 (!!!) feature matrixes. :-)

[Cross posted on http://www.agilior.pt/blogs/tiago.pascoal/archive/2008/03/05/3826.aspx]