When I was down at KFC today, the manager was talking to staff about specials using a customers mobile. I thought maybe it had something to do with Foursquare, or an app for iPhone/Droid users. A bit of further investigation has revealed you check in using Facebook to gain the special, just flash your phone to a staff member when ordering.
Not sure how long this has been going on for, but looking at their facebook page and the fact that people were being "inducted" on it, I would say not long.