Isn't a Wiki kind of vulnerable to trolls and vandals?
If there's no security measures to it, yes it could be possible.
The one I linked to, GBPVR, was originally set up so you'd have to be a registered member of the site, then if you wished to add something, you submitted it, and (I'm guessing, but this is what I'd expect to happen) it was proofed to make sure there wasn't an attack on another member, a spamming for another site, or obscenity. That really only required a cursory look, and if it wasn't going to be added, notice was given to the member as to why (You can't say so-and-so is a jackass or XYZ's software is a piss-poor option compared to everything esle), and it wasn't entered. Fix it and resubmit it.
Over time, when it seemed to be up and operational with very few problems, it kinda shifted. I think anyone can add something to it now (well, you still have to be a registered user of the site to be able to update the wiki)
Correction would be made by members finding a step missing, additional info given, etc.
Saint, from what I've seen, it seems to be just an editable page with limited priveledges for that page only. Access has to be requested, an e-mail is sent with the wiki edit area, and a unique password is given within that e-mail. Mebbe that's how they tracked users/editors/authors and limited problems.