Posner calls serious errors by the mainstream media as breaches of trust:
Inaccuracies in blogs are less pernicious than inaccuracies in the mainstream media even apart from the superior opportunity for prompt correction of bloggers' errors. The reason is that bloggers are known not to employ fact checkers or editors; there is no pretense that they have the resources to eliminate all errors in their postings. The mainstream media, in contrast, represent to their public that they endeavor assiduously to prevent errors from finding their way into articles and broadcasts. They ask the public to repose trust in them. Bloggers do not. That is why serious errors by the mainstream media are played as scandals; they are not merely mistakes--they are breaches of trust.
I couldn't agree more!
Update: Derek Rose disagrees as he thinks that bloggers should be responsible for what they write and should be held accountable. My response is that bloggers present themselves as a network. The debate conducted by bloggers through the network of posts linking to each other as a whole makes more sense than a single post on its own. This is unlike newspaper articles which generally stand on their own and the sources cited (case in point, the Newsweek's article about Kuran abuse). This is an important difference. I haven't seen many cases where inaccuracies in any newspaper article were exposed by another newspaper. But in case of bloggers it is routine to comment and debate among each other.