I stumbled across a game called Ingress the other day on Google Play. Turns out it's very interesting on many levels.
First, to my knowledge it's the first augmented reality game for mobile phones. Not just real-time but real-space.
Second, it's run by Google.
Third, Google are now starting to market it after a year in beta. They're bundling promo stuff about it with new Android phones.
Fourth, given there are already a good number of people playing it (in Bristol, UK, where I live the main areas around town are live battlegrounds) you can bet your bottom dollar Google will start trying to make advertising money from it at some point.
Fifth, until they start making advertising money from it there are opportunities to get free marketing for your local business by setting up a portal next to your premises.
http://searchengineland.com/ingress-googles-ar-game-a-stealth-local-data-effort-175417Ed
PS It's also a very addictive game. I feel like James Bond sneaking around hacking into portals.