Workers who use the web for entertainment while at work — whether they're tweeting, watching YouTube videos, shopping, or catching up with the news — are 9% more productive than those who don't, according to a recent study by Professor Brent Coker at the University of Melbourne. (As long as they don't spend more than 20% of their time in the office doing what Dr. Coker calls "workplace internet leisure browsing".) Why? People need quick breaks in order to maintain a high level of concentration throughout the day.
Source: The University of Melbourne

Ну вот, теперь есть обоснованное оправдание коротким вылазкам в жж, контакты и прочие фейсбуки :)