The short answer is yes, some point and shoot cameras can all be rigged to one remote trigger.
Do a Google search for "CHDK". It's a firmware hack that runs on top of the existing firmware in most Canon compact cameras. Among other things, it allows you to look at the state of the +5V line on the USB port, and take action based on it. The upshot is you can set that up to trip the shutter. I know people have used this to build stereo photography rigs where both cameras trigger together. I don't know what the practical limit is, though, for the number of cameras you can chain together this way.
CHDK lets you do a lot of other things besides triggering off the USB port, by the way. Lots of other scripts like intervalometers, focus bracketing, etc. might be useful for Photosynth.
P.S. What's a bullet-time rig? Do you mean something along the lines of Doc Edgerton's bullet going through an apple?