Photosynth is just cool! Now you can make your own photosynth and show it to your friends. It's certainly enjoyable to explore these synth's that they have online. You'll have to download a browser plug-in for the viewing experience (just takes a minute), and then it's time for the 3D viewing extravaganza.
If you want to build a synth, all that you need is an average digital camera - and a bunch of pictures of something. Be sure to get a bunch, i.e. more is better (for the viewing experience). Upload to the site, and bam!
Check out these resources.
Currently, the Photosynth site is going gang-busters and they are only showing photosynth's (and not uploading). But, that should change soon. In the mean time, just hit refresh to see different photosynths. There are many cool ones, but had to check out Fenway Park.
Also look for the virtual ring. If you see it, grab it and experience 3D viewing in a way that you might never have with individual pictures.
I'm running this on my Vista x64 (Lenovo T61p) and this runs great. Very cool experience. I can't wait to build a synth of my own.
If you want more information from a outsider's perspective, see this CNET article. The article also includes a CNET video demonstration with Dr. Gary Flake, Technical Fellow with Microsoft, one of the smart people involved in this effort, where they take pictures of this studio and upload to Photosynth.
Gary and Photosynth come from Microsoft Live Labs, home of many other cool things like Seadragon, Deepfish, Volta, Listas, etc.