This is a new technology being developed for the new smart phones. Now, Qualcomm is implementing this technology in Android smartPhones. Long story short, check this video.
I remember a game on PS3 called Eye of Judgement which had the same principal; seeing the same thing on a smart phone is pretty impressive.
Also, if you are familiar with an App–Android– called Layer which lets you take pics of a certain place then you put a layer of information about this place.