In response to a question about whether students and researchers should cite Wikipedia, Wales says:
No, I don't think people should cite it, and I don't think people should cite Britannica, either -- the error rate there isn't very good. People shouldn't be citing encyclopedias in the first place. Wikipedia and other encyclopedias should be solid enough to give good, solid background information to inform your studies for a deeper level. And really, it's more reliable to read Wikipedia for background than to read random Web pages on the Internet.
It's really a key point: Some people put down Wikipedia for its inaccuracies. (Although Nature just came out with a report saying it is almost on par with Britannica on science entries.) But that misses what Wikipedia is all about. It's a place to start your research. Don't count on it as being correct, but realize that more often than not it is.
The internet is full of misinformation. At least Wikipedia has built a system that has a degree of accountability -- anyone can correct others' errors -- unlike most of what we run across on the web.