Kamikazee: Travelling slower than the speed of light, since the light from behind would hit you at such a slow speed, it would take a long time for it to get back to it's source, but you would still be visible eventually. It would just be delayed. However, travelling at the speed of light, there would be no way the light could be reflected, only stopped, therefore you would be invisible to those behind you.
I know what you're saying about running into light, but if you were travelling faster than the limit that light can travel, you would be invisible until slightly after you reach the target. I think you would also appear to be moving backwards to the target as the light reflected would be received in reverse (the light from far away would still be catching up because you're travelling faster than it)... Ow, my brain hurts.