From News@Nature:

Wikipedia is growing fast. The encyclopaedia has added 3.7 million articles in 200 languages since it was founded in 2001. The English version has more than 45,000 registered users, and added about 1,500 new articles every day of October 2005. Wikipedia has become the 37th most visited website, according to Alexa, a web ranking service.

But critics have raised concerns about the site's increasing influence, questioning whether multiple, unpaid editors can match paid professionals for accuracy. Writing in the online magazine TCS last year, former Britannica editor Robert McHenry declared one Wikipedia entry — on US founding father Alexander Hamilton — as "what might be expected of a high-school student". Opening up the editing process to all, regardless of expertise, means that reliability can never be ensured, he concluded.

Yet Nature's investigation suggests that Britannica's advantage may not be great, at least when it comes to science entries. In the study, entries were chosen from the websites of Wikipedia and Encyclopaedia Britannica on a broad range of scientific disciplines and sent to a relevant expert for peer review. Each reviewer examined the entry on a single subject from the two encyclopaedias; they were not told which article came from which encyclopaedia. A total of 42 usable reviews were returned out of 50 sent out, and were then examined by Nature's news team.

Only eight serious errors, such as misinterpretations of important concepts, were detected in the pairs of articles reviewed, four from each encyclopaedia. But reviewers also found many factual errors, omissions or misleading statements: 162 and 123 in Wikipedia and Britannica, respectively.

...via Smart Mobs