The article considers two situations where group wisdom is tapped using a simple democratic process, and shows that it works in one instance and doesn't work in the other. A more interesting question, and one that is far broader in scope, is to try to identify which community structures amplify individual wisdom and which structures diminish it. Wikipedia and Slashdot would probably be extreme examples -- the former has built something remarkable by leveraging the collective wisdom of unremarkable individuals, whereas the latter has managed to take people who are smarter than average and reduce the discourse to juvenile banter. This should be interesting to people here, since Hacker News is an experiment in this vein. But I think the issue is important enough to merit rigorous study, so that people who are building various types of social sites can start with an idea of what kind of features to put in and what to leave out.
I speculate that the type of structure is the major factor causing the quality of social interaction to diverge. Wikipedia is people collaborating to make something, and only incidentally communicating with each other, on talk pages and user pages and so forth. Slashdot (and all its ilk, including Reddit and HN) is primarily people communicating with each other on comment pages. (I disregard story voting here because they don't have the same process, but also because voting is a relatively trivial input for a user, whereas writing a thoughtful comment/profane flame takes significantly more effort.)
In a nutshell, Wikipedia's product is not communication between users, so the Greater Internet Fuckwad Theory (http://www.penny-arcade.com/comic/2004/03/19/) finds less purchase. Slashdot/Reddit/HN do produce such communication, and then micro-optimizations determine the course such communication will take, like the moderation details/ability to downvote/etc. That's my hypothesis, anyway.
