Granted, you have to register and log on to make changes, but I think
it is better than most departmental sites.
I have also seen collaborative research projects set up internal
twiki sites for grant application and grant excecution.
I can see three flavors of a Stata wiki site:
(1) Convert all UCLS ATS pages to twiki pages, with restricted access
to those pages already present by UCLA ATS faculty but then linked to
pages open to the public for comments or anything on topic.
(2) A Stata Corp twiki site open to registered users of Stata (serial
number being your password).
(3) A completely independent and open site having nothing to do with
(1) and (2).