on the other hand, when someone updates a wiki entry, there is little visibility to the update operation, and pretty soon you are talking with yourself.
of course, discussion should eventually mature and consensus migrate to the wiki.
it also helps if discussions make frequent reference to the wiki, because it attracts more traffic, and the assumption is that some of the readers will stop and edit the wiki.
of course, the perversion on top of perversion is that the wiki contains a "discussion" link.
if i knew how, i would change the "discussion" link of the wiki to point to the appropriate thread in the forum...
ideally, pressing "discussion" in the wiki will look if appropriate topic exists, and will either open the "New Topic" or "Reply" accordingly.