Website with youtube video: http://runway12.com/projects/XPlaneOculus/
This is a plugin for X-Plane that adds support for head tracking with the Oculus Rift virtual reality HMD.
3D rendering for the rift is not currently supported. I'm using Ibex to convert the X-Plane window's image to the format needed by the rift for now. It's not a perfect solution at all, but it's good enough for initial development.
Support for rendering in stereo 3D with the correct dirstortion for the Oculus' optics is a planned area of research, but may not be possible from an X-Plane plugin. Positional headtracking using a head mounted Razer Hydra is also planned.
Things are in pretty rough shape right now. Expect things to get better and more documentation to come after a few more hours of hacking.