About 10 years ago I did a lot of stereo photography with various rigs including the Stereo Realist camera, and also a nifty optical beam splitter device that was made to fit on one of my Leicas. The technology involved is really very simple; two simultaneous exposures with lenses (or mirrored prisms) placed to produce parallax views. The trick is in viewing the prints (or slides); you need an appropriate viewer in order to see the 3D effect... (Think Viewmaster here).
-Paul Data