Photosynth is a new (and great) 3D photo tool from Microsoft Labs. It was only released yesterday and although they have had some problems, it is a great tool to have a look at, even if you just want to browse other peoples photos. However it is very easy to create your own 3D photo collection. I made a couple myself. Here is a “synth” from our recent trip to Ephesus, a Greek archeological site in Turkey. Have a look yourself.
PS. You probably have to install some browser extension the first time you go into Photosynth.