Hi, <plug> http::/www.cpanforum.com while not a wiki tries (in the TODO list at least) answer some of what you are looking for.
Specifically I though of setting up - with the help of the users - "groups of moudules" or categorizes from within th list of all the modules on CPAN and then allow discussion per such larger group. I think these groups could be overlapping as there are modules that will fit several categories. While it is not a wiki and does not allow co-editing of documents it can let you "write articles comparing sets of similarly themed/purposed modules." Gabor
