On the assumption that strangers may not make it easy for us to escape our pasts, Acquisti is also studying technologies and strategies of “privacy nudges” that might prompt people to think twice before sharing sensitive photos or information in the first place. Gmail, for example, has introduced a feature that forces you to think twice before sending drunken e-mail messages. When you enable the feature, called Mail Goggles, it prompts you to solve simple math problems before sending e-mail messages at times you’re likely to regret. (By default, Mail Goggles is active only late on weekend nights.) Acquisti is investigating similar strategies of “soft paternalism” that might nudge people to hesitate before posting, say, drunken photos from Cancún.

http://www.nytimes.com/2010/07/25/magazine/25privacy-t2.html