I think we're starting to see wikis encroach on newsgroup territory, but some development of these types of wikis need work.
Newsgroups are so 90's
I've always found newsgroups to be disjointed, difficult to search and post followup is sketchy at best. Half the time you end up with answers from people that didn't grasp the original questions and no one pays attention to the post once a response appears. Problems are constantly restated (users not searching the newsgroup before posting) and reply quality varies greatly.
Enter the Wiki
I believe the answer lies in having a community that directs itself to some degree. On Microsoft's groups, I see the MSMVPs who have a somewhat vested interest in driving the newsgroups spending their time sniping recurring newsgroup posts. A wiki solution would allow for submission of articles that cover recent posts. These articles could come from anyone, but some type of review would be needed to ensure quality. This way the community can respond to the change in usage patterns that the original vendor does not necessarily control, endorse or anticipate.
The structure could resemble the existing structure with one caveat. The wiki “community” should be able to spawn sub-communities as needed. For example, microsoft.public.dotnet.framework.interop could spawn a sub-community called “.distribution“ if participants were posing a large number of distribution questions focused on interop. This keeps the group focused and able to maintain some sort of direction to the newsgroup by keeping the areas clearly focused while serving needs that may change over time. Duplication with the distribution newsgroup needs to be handled with care, but the content can reference the other site where necessary and communication isn't that difficult.
The wiki still needs the ability to accept posts, but the focus of the site is on searching existing material (articles first, posts second). The NNTP protocol could still be supported, but I question whether that is a good idea. Given this specialization, perhaps a better name than wiki is needed. The term “wiki“ is far too general, annoyingly ambiguous and has a “geek's only“ ring to it. It is the 'Pat' of current webspeak - referring to the old SNL skit. Calling this type of site something completely silly like a “lighthouse“ would be more informative than “wiki“!
So who mans the lighthouse?
The question becomes who drives this site. Seems to me it's a perfect extension for the platform vendors. If you consider the MSDN site, this would be a content generator for the site. As new wiki articles are posted in response to community issues, these become fodder for content inclusion by the vendor - allowing the development community to help drive the platform docs. Personally, if I were an MSMVP (I am not) I'd be far more interested in monitoring/mentoring a community than simply responding to random posts on a newsgroup. But that's me.