insecurity in the www

"It's also critical to remember that once you put data online, it's almost impossible to delete it later. The more you blog about yourself, the more details you put in your social networking profiles, the more information about you is being archived, copied, backed up and analyzed almost immediately. Think first, post later."

This is actually from an excellent article in Scientific American, by Herbert H Thompson: 'How I Stole Someone's Identity'