Nature magazine did a study last year where they compared Wikipedia to Encyclopedia Britannica.
They chose a series of random articles that existed in both and had them extensively scrutinized by teams of experts, and had some interesting results.
The Britannica articles had slightly fewer errors, and the Wikipedia articles were slightly longer, but they were roughly equivalent in accuracy.
The Essjay situation that started the thread was a disgrace, and he was asked to resign and his access rights were revoked. The community was furious about it, and a discussion about how credentials should be verified at certain levels in the project. I think it's telling that in this entire mess, there's been no evidence that he used his false credentials to insert false information. Apparently he waved them around in some discussions to win editorial arguments, but the accuracy of the data in the project was not affected.
Despite this, the reaction has been quite telling. As I see it, there are a number of people out there that have a bone to pick with Wikipedia because of a personal slight (perhaps their article was deleted or something like that) or assume that it must by necessity be terrible because they can't imagine that the anonymous editing structure would allow for quality.
To the latter, I urge you to go check out some articles on subjects that you know about and decide for yourselves. For the former group, give it another shot, things change, and maybe other areas of the project might still be useful to you. There's plenty of room.
