Interesting question. I don't have an answer per se, as in my mind it would depend on the magnitude and direction of the vibration. I suspect that IS would, but your camera would be battling its system that is supposed to detect if the camera is on a tripod and turn IS off and the slight movement that it would adjust for with IS.

Your question also got me wondering about the benefits of carbon fiber legs on your tripod. They are supposed to be far better than aluminum at dampening vibrations. I wonder if you could feel/see the vibration, but your camera...nothing....all due to the CF tripod.

If you are ever in that situation again, I would be curious if you could feel the vibration in the railing, then touch the top of the tripod, and if you feel it there or not.