Photosynth software takes a large collection of photos of a place or an object, analyzes them for similarities, and then displays the photos in a reconstructed three-dimensional space.
+++ Photosynth not for MAC users at this time... sorry (but it works on FireFox)
No idea about the technology behind Photosynth, but it's hard to imagine that this can be done without extensive human manual work. Anyway – the software finally makes use of millions of digital images found in photo sharing sites like flickr.(see the Domus d'Autore posting on anarchitecture)
Photosynth raises digital photography and the perception of space to another level. It's kind of unfair: if this application wouldn't be invented by a company recently acquired by Microsoft it would raise an enormous hype in the online world.
Maybe software like Photosynth stops the inflation of architecture photography and its slick images: millions of pictures definitely create a more honest impression of buildings than the press-images of architects.
See Blaise Aguera y Arcas doing a Photosynth presentation at the TED conference 2007. Really impressive!