From the U.S. Pew Research Center for the People and the Press: "Internet News Audience Highly Critical of News Organizations, Views of Press Values and Performance: 1985-2007." Findings released: August 9, 2007. Check out the table.
Jeff Jarvis sees the emergence of "media tribes" in this data, as it shows that using particular media influences one's judgment of the press (read: whether or not you are a FOX news fan). That seems to me more a testament to the effectiveness of News Corp market strategists rather than the emergence of a "new" social phenomenon. Market segmentation rules, also in news. Indeed: citizen journalism (or, as Jarvis argues, "networked" journalism) is also just another market strategy. That does not make it bad per se, but let's not kid ourselves otherwise.