Just want add with my experience.
I needed stereo for scientific visualization and have ended up using ATI Radeon + Eye3D glasses + Xi-graphics driver. This gives me nice quad-buffered stero under linux.
It will be very nice to see how the new ATI cards perform - but still it would very nice if nVidia put a little more effort into stereo support in linux.
I gave up on nVidia cards - it was only possible to get scanline interleaved stereo under linux.