Originally Posted by
SIAMEX
As someone who has developed Facebook applications with similar use cases, Facebook is not getting knowledge of your AMEX account, rather its the opposite being done: AMEX will have access to your Facebook data and can likely make targeted offers and creditworthiness decisions using this new data, along with all the other information they have on you.
I've signed up a few promotions where I had to "like" the company's page. In this case, I have to link my Amex card to the FB account.
Creepy!