This has rumbled on for a long time.
I fall more in the pro than the anti camp, but with reservations.
I am not convinced by claims that Wikipedia is as accurate as Britannica, and it would be very surprising if they were true. The "latest snapshot" of Wikipedia cannot be authoritative in the way a managed encyclopedia or a textbook can be, and I am disturbed to see Wikipedia cited in scholarly articles or legal opinions.
However, to me those aren't the main point. Wikipedia is not really in competition with premium encyclopedias or university-level textbooks - its easy availability and massive scope put it into a different category. It makes more sense to compare it with other casual ways of gathering information - conversations in the pub, the popular press, TV programmes, memories of junior school lessons.
In my opinion, we get most of our information about most subjects from sources considerably less reliable than Wikipedia. Take the question of of early-20th century history I mentioned last week. My first source of information was a historical novel - low reliability. Next was Wikipedia - surely more reliable than a work of fiction. Thirdly I discussed it with my wife - not in general a high-reliability source, but since I happen to be married to a history teacher, the source has a certain authoratitiveness. Less detailed, accurate, information, in fact, than Wikipedia, but, while it is possible that Wikipedia might be seriously misleading or incomplete, it is less likely that a history graduate, even one rusty in the particular subject, would be so.
But authority is a niche market, though an important one. When you need an authoritative answer, nothing else will do. Most of the time, you don't. Unless you have a good reason to find an authoritative answer, you're not likely to find one - they don't grow on trees.
The other question is how much better Wikipedia will get. I think the answer is not much - it has grown rapidly to the limits that its structure puts on it. The organisers will continue to tweak the rules to balance new contribution, vandalism and editing, and it will continue to expand in scope, but the basic level of quality is probably about where it will remain. As I've said, that quality is very high for most purposes, but not high enough to displace truly authoritative sources of information.
A couple of asides on possible derivatives of Wikipedia: It might be possible to take a snapshot of Wikipedia as a starting point for producing a truly authoritative encyclopedia - it would probably be easier to check the articles there than produce authorititave ones from scratch. Such a product would compete with "real" encyclopedias, but would not compete so much with "live" Wikipedia, which gets much of its value from its currency.
Also, I'm not up to speed with current work on A.I., but I've tended to the view that a missing element is the very large amount of stuff you need to know to have any kind of ordinary conversation with a human being. I can't help wondering whether the enormous database of "general knowledge" that is wikipedia might at some stage form a key part of the first natural-language speaking A.I.
Update: Tim Bray makes the point that Wikipedia's popularity as a reference is partly due to the fact that those who could provide authoritative information in the public domain aren't doing so in a sufficiently organised way.