This seems to one of the latest trends in the web based world. It's called augmented reality. This is the ability to look at your surroundings and have technology enhance what is already there with new information. To get a sense of what this could be, take a look at this video from the labs at Google Maps.
Of course Google has taken that a step further with Project Glass:
Google founder Sergey Brin has been out an about showing off the prototype which may be available next year: