As of now:
They allow you to open your room door by tapping the key against the pad instead of swiping the card or sliding the card into the door.
http://**************.net/wp-content/uploads/2012/06/RFID-Key-Card-and-Lock-at-Disneys-Art-of-Animation-Resort.jpg
They allow you to tap your key on a pad for park entry.
http://static.attractionsmagazine.com/wp-uploads/2012/12/rfid.jpg
They also allow you to charge purchases to your room by tapping it against a pad instead of swiping it like a credit card.
http://www.wdwforgrownups.com/sites/default/files/images/rfid.jpg
No tracking of your location.