The University of New Hampshire released a study examining the correlation between student's time devoted to Web 2.0 and their grades. Their findings? None. Their was an even distribution between students who considered themselves "heavy users" (more than an hour a day) and "light users" (less than a half an hour a day).
This seems to make sense. It comes down to time management, and there have always been ways to distract oneself from their schoolwork. Twenty years ago is was Super Mario Brothers, ten years ago it was spider solitaire and minesweeper, today it is mafia wars and facebook.
What is interesting is that 92% of the student who participated in the study were all on facebook.
As I said earlier, Big Brother has a new name, and it's Mark Zuckerberg.