Currently GPBikes doesn't support NVidia 3d vision technology. It would be great to implement this functionality in future releases. I've tested it in LFS and rFactor, it dramatically improves the sense of speed and overall experience.
Nvidia 3D Vision doesn't support OpenGL, so nothing can be done, unfortunately.
There is an openGL implementation example here
http://www.nvidia.com/content/gtc-2010/pdfs/2010_gtc2010.pdf
Page 10
Thank you for the report.
It seems like Nvidia added quad buffers support for consumer cards since driver version 314.