I like the idea (++) and have even used the idea myself in the past in the Tk::JComboBox docs, and plan to implement it within other modules I publish and/or maintain. However, I disagree that Perlmonks should be where this information is kept. It should be in the docs. Barring that, I think AnnoCPAN is the best place for others to add this information. AnnoCPAN provides a mechanism that can provide feedback to module authors, and even if authors don't add it, the annotations remain "close" to the documents through the service.
If you're looking for something to place on Perlmonks, I think maybe a longer tutorial or article (similar to the survey you mentioned) that goes into more depth might be worthwhile
Rob
