Good news for iPhone 5S customers! The fingerprint reader will only work with actual live fingers, so you don't need to worry about some James Bond supervillain wannabe cutting off your finger in order to get access to the iPhone he's stolen from you.
Actually, it's even better than that, since a thief would have no idea which finger you normally use and would therefore have to chop off both your hands to really be sure he had the right fingerprint. But you don't have to worry about that either. Your digits are safe.
(Assuming that iPhone thieves all read Mashable, that is.)