Besides playing 3D-material, modern 3D-TV-sets (using polarization technology) offer the possibility of dual-play.
While 3d-playback works with different polarization for the left and the right eye, with dual play 2 users can watch completely different 2d-material at the same time on the same screen. To make it work, each of the 2 users gets different glasses: one is horizontally polarized on both eyes, the other is only vertically polarized. By now, this technology is primarily used for 2 player games, to replace split screens.
My idea is to use this technology for a multiseat system (I would prefer using Debian).
For a multiseat-setup, one usually needs 2 keyboards, 2 mice, 2 video-cards and two screens, but when using a 3D-TV-set, one video card (and of course just one screen) should be sufficient.
Therefore, apart from the "normal" setup of a multiseat system, the major difficulty would be to get the two different video-signals to the TV-set like if they were just one stereoscopic signal. One possibility would be to send the two signals side-by-side or over-under.
So basically, the goal could be achieved with a setup like in this video but with display settings for a 3D-TV (and with a modern operating system, best would be debian with gnome 3).
Finally, I want to add that I don't own a 3D-TV yet, therefore I cannot verify your answer. Still I would be glad if somebody could discuss the feasibility of such a system.