This paper, Meme-tracking and the Dynamics of the News Cycle, in which computer scientists from Cornell and Stanford tracked a series of short phrases appearing in the news cycle and observed their journey back and forth between MSM and blogosphere, certainly looks worth further study. But the quick take away message:
1) Phrases appear in the MSM on average 2.5 hours before they show up in the blogosphere. That is, the "news" tends to be "discovered" by real journalists, and then propagated further, at a slight lag, by the blogosphere.
2) Only about 3.5% of news stories move from blogs initially and then into the MSM.
Well, I was rather hoping "we" would be doing a bit better. But the dinosaurs still rule, it seems.
The meme-tracker in question can be found here.
(Haven't read the paper closely enough to see if this would actually pan out, but 2 1/2 hours is about the time between when most bloggers read their news in the morning and the time they write about it.)