Ramblings

Media hypes a study showing a negative correlation between Facebook usage and GPA.
Professor notices and posts comment on Twitter, at her blog, and at Facebook.
Other professors begin commenting, culminating in a joint paper published in a peer-reviewed journal saying that the evidence is weak at best, and that besides correlation is not causation.

I'm going to go out on a limb saying that the guys who published the first study didn't really anticipate Facebook and Twitter being used to organize a critical review to be published in a peer-reviewed journal within 20 days. They say one counterexample is enough to disprove a hypothesis - this might have been a bit much.