I created a patch to display Celestia in stereoscopic 3D.
Here it is running on our passive 3D display wall (16 HD TVs, total 8k resolution!):


Framerates are quite good (30 Hz+), especially considering that in quad-buffered OpenGL the GPUs are rendering the whole 8k scene twice for left and right.
We are using 4 NVIDIA Quadro K6000 cards to drive our display wall. It should also work on simpler setups (e.g., GeForce + 3D Vision) but has not been tested.

One thing I noticed is that planetary surfaces appear very flat, because normal mapping only creates the illusion of bumpiness via shading.
I would very much like to add real displacement mapping, combined with a terrain LOD scheme such as projective grid mapping (PGM) and shadowing via shadow volumes, etc. This would be a big project, but would make stereoscopic 3D much more useful.

While I wrote the patch for Celestia trunk (since .Sci is not yet ready for public distribution), it should be trivial to apply to .Sci as well.