Facebook unveiled a new security feature that would require a Facebook account holder to identify their log on devices so that if a Facebook account is accessed from a device that is not on the approved list, it will trigger an alert.
The person who logs on from the unapproved device will have to answer a security question which will not be difficult to answer if he is the real account holder. Some of the questions that might get asked, besides the security question if it was provided, could be the date of birth or even to identify a friend in a photo. This could be rather tricky even for a real account holder because some people do not use their real name on Facebook.
Anyway, if you think this is feature is useful to you and could help prevent your Facebook account to be accessed by unauthorized people, you can look out for the feature under your Account Settings page.