The Google Maps blog announced that Google has extended their maps details to add over 25 million new buildings footprints to Google Maps across the United States.
The new building footprints are the outlines you see on Google Maps of buildings as you zoom into a location on map view. Not the satellite view. The new buildings were added to Houston, Los Angeles, Chicago, Miami, and the San Francisco Bay Area.
Google says the building footprints are "algorithmically created by taking aerial imagery and using computer vision techniques to render the building shapes."
Forum discussion at Google+.