As of the FB app on my iPhone, when I wanted to connect it with my phones data (to get extra phone numbers of my friends, and see their profile pics), I was asked to agree that the app can upload the data to FB and let them use it whatever way they want to. (Read: all the phone numbers in my phone, not in the FB app.) That really blew my mind. I didn't agree, but if 500 people have your phone number in their phones, the chance that none of them agrees is zero.