I've mentioned Photosynth a few times, and I had a mail this morning which said we've have gone live with a public version. You can read the press release here, but really just go to http://www.photosynth.net/ . Have a look at what others have done, but I'd really encourage people to try it : you'll see the words "Create your synth" at the bottom left - Click it, install it, Enjoy it.
I've had access to some pre-release versions and I need to rebuild them for the public site, links will follow shortly.
Update. Thanks to Steve J and Matt M for pointing out the typo in the link. Fingers not as fast as Brain - and not for the first time !
Update 2. Yesterday I the documents I had were using the .COM address, which redirected to Photosynth.net. The site seemed to have a few first day nerves, and this morning the .com redirect is not working. (Sigh. Go straight to photosynth.net)