This is a very good analysis of "memogate" - how it happened, the involvement of bloggers and the MSM, and some background. Good read.
Blog-Gate
Yes, CBS screwed up badly in ‘Memogate’ — but so did those who covered the affair
Bloggers have claimed the attack on CBS News as their Boston Tea Party, a triumph of the democratic rabble over the lazy elites of the MSM (that’s mainstream media to you). But on close examination the scene looks less like a victory for democracy than a case of mob rule. On September 8, just weeks before the presidential election, 60 Minutes II ran a story about how George W. Bush got preferential treatment as he glided through his time in the Texas Air National Guard. The story was anchored on four memos that, it turns out, were of unknown origin. By the time you read this, the independent commission hired by the network to examine the affair may have released its report, and heads may be rolling. Dan Rather and company stand accused of undue haste, carelessness, excessive credulity, and, in some minds, partisanship, in what has become known as “Memogate.”
But CBS’s critics are guilty of many of the very same sins. First, much of the bloggers’ vaunted fact-checking was seriously warped. Their driving assumptions were often drawn from flawed information or based on faulty logic. Personal attacks passed for analysis. Second, and worse, the reviled MSM often followed the bloggers’ lead. As mainstream media critics of CBS piled on, rumors shaped the news and conventions of sourcing and skepticism fell by the wayside. Dan Rather is not alone on this one; respected journalists made mistakes all around.
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http://cjr.org/issues/2005/1/pein-blog.asp