A recent article in Nature looked at 42 entries about scientific concepts in both the Encyclopedia Britanica and Wikipedia and have found that the latter is almost as accurate as the former, with EB having 3 errors per article to Wikipedia's 4.

Further comment is made by some information scientists about the readability and organization of the articles on Wikipedia, and (of course) a slightly- disparaging remark by EB), but there's also mention of the speed with which Wikipedia can be updated.

Another thing that I find interesting about Wikipedia is that it provides entries for items that would be excluded by EB because of either lack of domain knowledge (Telnet) or interest (SCA).

All things considered, a more in-depth discussion of the historical articles would be of interest to me. I'd be interested in knowing how much of the history is "questionable" and how much is "accurate", but these things are always hard to gauge.