The recent TED conference featured this demo of a Microsoft sponsored project. It gathered photographs of Notre Dame on Flickr, analyzed the images to determine their spatial relationship to the building, and built a seamless, panoramic, three-dimensional representation.
Think about this concept. You are on vacation and take a picture of a landmark. After you upload it to Flickr, the image is matched with other images and the metadata is shared. Eventually, we will have virtual representations of the entire globe, not from an anonymous airplane or satellite but from the viewpoint of people.
Here’s a video that describes the project better.