The Wikipedia history of medicine article is probably not something I would like to give to my students to read. The quality of the auxilliary articles are also quite uneven. Some of them are really bad, e.g., that on the history of anatomy or the “article” on the history of immunology (my own specialty!) which is reduced to a simple list of chronological events.
But other articles are surprisingly informative, e.g., the article on the history of neuroimaging. And generally, the articles on recent biomedicine are much better than the articles on earlier historical periods — a tendency which supports the impression that Wikipedia is good in science and technology and bad (sometimes even awful) in the humanities.
That said, I believe that the Wiki concept is the future for dictionary production in our field. After all, most of my students start (and sometimes remain) with the internet when they are looking for information for essays. We may indeed have a whole battery of good reasons to discourage them from doing so (“unauthorised information”, “lack of critical review”, etc), but I don’t think we can stem the tide. So — if you cannot beat them, join them! Write good (and better) articles! Bombard them with well-researched and well-written contributions!
And most importantly, I think we should launch a campaign to force Wikipedia to introduce signed articles — in fact, I believe this is the single most important step that would immediately make Wikipedia the most useful and authoritiative web-based dictionary, even for scholarly use.