Photosynth combines hundreds or thousands of regular digital photos of
a scene to present a detailed 3D model, giving viewers the sensation of
smoothly gliding around from every angle.
There are a few videos to watch about how the thing works and the usual seamless demos but there is some real exciting stuff here. They kind of suggest (and it isnt a huge leap of logic to imagine) the idea that with some Geo-tagging you could harvest content from set ups like Flickr and then re-construct places, events etc.
Forget Second Life. Imagine taking all of the citizen journalism images of the Buncefield refinery fire or the recent US forest fires and building a virtual, visual news archive to walk through.
Now, imagine that with a nice aqua interface and dual core support and you have my idea of a killer app.