The existing tag wikis are not enough. They can only store a very small volume of information, and given the complexity of the topics we're discussing here, that's just not enough.
I propose to make them full wikis- that is, full community-edited sub-sites in their own right to host various reference material that does not suit the main site's Q&A format.
Edit: I mean that specifically, the community would be able to create, delete, and edit pages pertaining to the tag in question. Permissions to do this would be based on reputation in that specific tag, rather than in general.
Yes, the functionality, at its core, is similar to Wikipedia. But it's not really similar in usage. Consider some of the reference material due for deletion. The Definitive C++ Book Guide and List, for example. You can't find that kind of material on Wikipedia. The tag wikis would be much more specific.
Ultimately, not every piece of helpful material ever is in Q&A format. Some of it is reference. The question is whether we're here to help people, or just answer questions. For example, there are C++-FAQ questions on the site right now which could, more accurately, live in here.
More accurately, the problem is that we have existing material which is not really Q&A, it's reference, and doesn't belong. It can't go in the tag wiki because the thing is just a Giant Wall'o'Text. All we need is a little subdivision so that we can link to specific sections.
As for competition with Wikipedia, it's not even close. Consider operator overloading. Wikipedia has about 4 lines covering operator overloading in C++, which basically state "You can overload XYZ operators.". The C++ FAQ has about 400 lines covering best practices in-depth. It is not really the same problem domain.