The Wall Street Journal has (under the rather pugilistic title "Full Text: Keen vs. Weinberger") a transcript of a debate between David Weinberger and Andrew Keen on the topic of user contributed content and web 2.0 generally. It's an enlightening read to see how two very different frames make very different pictures of (more or less) the same phenomenon. 

Keen, the author of The Cult of the Amateur, argues essentially that "Web 2.0's democratization of information and entertainment is creating a generation of media illiterates." Rather than being invigorated or enlivened by the contributions of a broader and broader set of participants, the web has become the home of "digital narcissism . . . personalized, chaotic media without that the essential epistemological anchor of truth."

Weinberger, the author (most recently) of Everything is Miscellaneous, argues that while it may be true that "because anyone can contribute and because there are no centralized gatekeepers, there's too much stuff and too many voices, most of which any one person has no interest in." But, he points out, "the Web is also the continuing struggle to deal with that problem." That is, our systems and frameworks for determining what is reliable and trustwothy also change in the web area, and the wisdom of the collective has a role to play in those mechanisms. 

Although the debate at times verges on the esoteric (does Keen's epistemology assume an external anchor to truth?) it is a set of concerns any online community manager ultimately confronts: is all this user generated content valuable, and in what sense or for what purposes?