jdef is on the right track with the human eye's sensitivity to green. The film is panchromatic and any colour light (in the visible spectrum) will fog the film.

The green safelight is used because it enables us to see well enough with very low light levels. You can use any colour safelight you want, or any light source including LEDs, but you must have a very small amount of light being emitted if you don't want the film fogged. You'll get the best results if you can turn the light on and off quickly without using your hands.

Sean's method has heaps of potential. I look forward to seeing how well it works.