Norm provides a fine and succinct summary of what is wrong with arguments about wikipedia et al.
I attended a very interesting session at the recent BAAS conference about Wikipedia, Google Scholar and research, with representatives from the British Library, Wikipedia and Google Scholar and a VERY full room of academics etc (it was one of the busiest sessions of the conference). Mostly we bitched about getting students to do any reading at all, let alone sufficient reading, let alone being critical of ALL the resources at their disposal (and not just the online ones). But there was certainly skepticism about the reliability of certain online resources.
The difficulty with wiki type knowledge is that is increasingly accepted by students as a reasonable substitute for broader research and increasingly not tolerated by academic staff as a legitimate source of information (in some instances even down to discouraging looking at it for inspiration, checking other sources recommended by it, let alone not citing it in a bibliography). This divergence is reaching something of a critical point, and one not helped by the sort of scare-mongering reporting cited in Norm's post.
I suspect at heart there is a psychological issue at stake here about the perceived over-democratisation of Web 2.0 in allowing anyone and everyone access to 'producing' knowledge. By making the process of updating and correcting knowledge not only more visible but also much much quicker, the old orders of power in producing knowledge have decayed somewhat.
Of course, undoubtedly there is a bit/lot of me that retains a sense of elitism about my love of books at which point I'm reminded of an exchange from Buffy - quel surprise! - where Jenny (techno-pagan and IT tutor) is talking to Giles (lovable fusty librarian)
JENNY: Well, it was your book that started all the trouble, not a computer. Honestly, what is it about them that bothers you so much?
GILES: The smell.
JENNY: Computer's don't smell, Rupert.
GILES: I know! Smell is the most powerful trigger to the memory there is. A certain flower or a, a whiff of smoke can bring up experiences... long forgotten. Books smell. Musty and, and, and, and rich. The knowledge gained from a computer, is, uh, it... it has no, no texture, no, no context. It's, it's there and then it's gone. If it's to last, then, then the getting of knowledge should be, uh, tangible, it should be, um... smelly.
I guess there will always be a strong part of me in love with books, with pages, but I'm fooling myself if I believe that they are inherently more reliable than judicious use of other forms of knowledge.