Regarding Wikipedia vs Ward's Wiki, and painting with the broadest of brushes, I'd say that Ward's Wiki is a wonderful practical joke or hypermedia art project, whereas Wikipedia is a project to create an encyclopedia that only incidentally uses Wiki technology – how many Wikipedia users know how to edit, let alone create, a page? 1%? 1‰? Put differently: Wikipedia has little place in a discussion of wikis in general, it's simply one successful application of Wiki technology.
I think wikis have one important feature: they put naming front and center; the rest (including "everybody can edit everything") is up for horse-trading. And that's where apenwarr's question is interesting:
How do you create a vibrant community, but allow for private topics and discussion, but allow for public topics and discussion, and allow me to work for more than one company at a time with multiple private discussions, and have my WikiWords always end up pointing where they're supposed to?Having your WikiWords always end up pointing where they're supposed to is of course a general AI problem. But I think there's some scope for principled approaches to naming in Wiki tech. More later, have to hack.