"For those of you with FaceBook accounts, and getting ready to upgrade to iOS 6 when it comes out, here's something else to worry about. iOS 6 will have the ability to sync your Contacts with your FaceBook friends. This is a two-way sync, so your Contacts (Address Book on older Macs) will potentially get a bunch of new information added. The problem is that FaceBook is scheming to increase the use of useless Facebook.com email addresses, and will send them to your Contacts. Check out the story for the details." This info from Prez Art Gorski. http://www.tuaw.com/2012/09/04/with-ios-6-your-address-book-may-be-invaded-by-facebook-com-em/