I stand corrected. Having now actually downloaded one of the dumps, I see it only contains the username of the most recent contributor to an article, not previous contributors. That's not good... shouldn't be too hard to fix, though - I'll take a look at the relevant code.
Odd... the code to include a list of authors is already there, it's just not being used. The variable that determines whether or not to include the list is just set to false, rather than being taken as a parameter. I'm sending this email to wikitech-l as well, hopefully someone there can explain why...