Yes, all outgoing links (as well as a few interior) are nofollow. The real link value is the scraper sites that only copy the plain text. Also, there's a lot of traffic-building involved.
It's more of an exercise in traffic building than in PageRank. But even still, of the thousands of Wikipedia "scraper" sites, how many do you think actually keep the "nofollow" attribute on outbound links?
Blah, I tried this but it was rejected. I've spoken a lot with the wiki editors and even if you have a legit site, if it covers areas that they consider spamish, you may get your article rejected. I would add that you have to sometimes spin your wiki so it falls in line with what the editors feel is "safe".