The social captcha feature Facebook is introducing is really cool. When you sign up for a new online account for any online services like social networking, etc. a security system called 'captcha' shows up where you retype some semi-scrambled letters and numbers you see on your screen. This is to differentiate humans versus computer bots trying to sign into an online system.
Facebook's going to start using this same philosophy for testing that you are the actual user on your account in case of a security breach. For instance, if you've logged into your account from Mumbai and then seemingly from Australia two hours later, Facebook's going to send you a security check to see if it's really you accessing your account. This feature will show you pictures of your friends that you will have to correctly identify. The philosophy is that hackers will know your password, but they won't necessarily know your friends.
While Facebook's commitment to security is admirable, it might be that they're doing it for accuracy of data for their advertisers.Obviously more accurate the data,more interested the advertisers will be!!good thinking,mark.