This happens to be one of the few areas discussed on these
boards where I feel comfortably within my zone of expertise. I
earn my living consulting organizations about how they can use
online tools to share knowledge. I've spent some time looking at
wikkis, and I'm not very impressed.
In there classic form, with no version control, wikki is an
interesting experiment with little practical value. Sure, it's easy to
post info, but it's even easier to write over that info or bury it in a
welter of poorly organized links. Self-organizing sites generally
don't work well in practice. The idea sounds great, but I've never
seen one work out to be useful.
Now, a system with more fine-grained permissions sounds
potentially more useful. But useful for what? As Tom points out,
I'm not sure I see what this could buy you that you couldn't
accomplish with file-storage, general comments, and related
links.
If somebody could give me a concrete use case, I might change
my mind, but I just don't see the value right now.