McDonald's created a billboard in Stockholm, Sweden with a Pong-like game called Pick n' Play that allowed people passing by to play using their smartphones. Players who did well at the game won coupons for free food at a nearby McDonald's store.
JWT Intelligence has a nice description and a short video showing people playing the game.
This is an example of so many trends - and the convergence of so many trends - it's hard to list them all. They include mobile computing, gamification, cloud computing, digital coupons, location based services, etc., etc. etc.