Now when I first used Facebook I used their system of uploading information from my Google Mail address book to find friends. Little did I know (and I would not have expected) that Facebook would retain that information after I’d used it for the purpose that I gave it to them for, and later use it to tell other people about me.
There’s 350,000,000 people on Facebook, and 600,000 more are signing up every day. How many of them do you think have read that? How many of them know what it opts them (and everyone in their address book) in to?