Breaking the Story First
Michael Cornfield did a study entitled "Buzz, Blogs, and Beyond." He wanted to research the effect of the blogs on the mainstream media, and the extent to which they affect each other.
The power of the blogs (if not already known) came to the forefront in the Rathergate scandal, in which bloggers (Powerline Blogger in Minneapolis) brought down a fake memo by CBS on George W. Bush's military service. It forced Dan Rather out of a job, and left CBS's image in tatters.
Cornfield said that blogs were successful because they had "the smoking gun" memo. Powerline and others were able to establish that the memo was faked based upon typewriter formats from the era in which the memo was said to have originated. Without "the smoking gun," Cornfield seems to state that bloggers would not have been able to impact the MSM to the effect of Rathergate.
I would argue that bloggers have always been on top of many stories, but that the MSM pays them little attention because of the gossip-like nature of the blogosphere. Rumors churn in the blogosphere before they even make the news. Matt Drudge broke the Monica Lewinsky Scandal story. Other bloggers broke the story about Congressman Schrock weeks before he resigned.
Those are a few examples of the investigative reporting of the blogging community - or either examples of unsubstantiated (and later substantiated) rumors that circulated before the MSM picked them up and found them to be true.
Cornfield is right that without substantial evidence, the blogosphere will not be a major source of news. When bloggers become reporters, as evidence shows they already are, the blogosphere might really break wide open the MSM's tight grasp on the news cycle.

