Rule number 1: don't trust Facebook or any other marketer with your information. Anything you provide should be carefully researched to see how safe it is then provided only after deciding what risk you face.
Rule number 2: don't usewithout even MORE careful research.
Breaking both rules is a new app from Facebook which will allow you (or one of your friends) to violate the privacy of many people at once by uploading your phonebook.
The greatest part is that you don't have to give up your phone number since one of your friends can instead! This is just like how Facebook let friends tell stalkers where to find you or add you to groups so someone who's mad at you can make you look like a pedophile.
Don't you love Facebook?