RE: "Augmented reality"
Coincidentally, I'm just re-reading "Spook Country" by William Gibson in which this technology features heavily. In the book it takes two forms: l"ocative art" and "hyperspatial tagging."
The first involves creating 3-D graphics which are overlayed on the real world when viewed through a headset linked to a laptop and a GPS unit. The idea being that things "appear" when you reach the designated location. I can see that you could use this to illustrate the impact of a new building (as per the artist's impressiosn we see now) or road scheme or landscaping project say.
The second, is about annotating objects at a given location with tags which are visible through the headset, rather like the key to a diagram. I think there's something similar available for the iPhone. You point the camera at your surroundings, the GPS picks up where you are and your view is overlayed with directions to the nearest pub or whatever.