Per a Macsurfer link... Deep Video Imaging is planning on introducing dual-layer monitors this spring:
Siegel said the 3-D environment is created by pushing light through two flat-panel LCD screens using a process that doesn't distort the images. The dual displays are built one on top of the other - with space in between - into one case.
Siegel said the monitors vary in depth depending on the type. For example, the ActualDepth displays designed for information kiosks have a 40mm separation, while screens for small hand-helds have only 5mm of space. But the effect is similar, Siegel said.
Related article: Apple: Stereoscopic Displays?