If you thought Google Earth was cool, check out the work being done by Swedish corp C3 Technologies. Using only photos shot from planes, they can automatically create high-resolution 3D models of entire cities that can then be explored. The above video shows a beautiful fly-by of New York City.
All of the C3 products are based on high-resolution photography captured with carefully calibrated cameras. For every picture, the positions and angles of the cameras are calculated with extremely high precision, using an advanced navigation system. This is what enables C3 to give each pixel its geographical position with very high accuracy. [#]
They can also apply the technology to turn panoramic photographs captured at street-level into 3D models of the scene that the user can navigate through freely. Hopefully this kind of thing makes its way to products like Google Maps soon. It would also be awesome for creating maps in video games!