When I was visiting the University of Texas in Austin, Prof. Stone gave a software demonstration of automated cars driving through an intersection. Since they were controlled by computers and could communicate wirelessly, there was no reason for stoplights and they were all zipping through pretty fast.

It will be cool when they have automated parking lots where you can pull up to the door and your car goes off and finds a spot. Then when you check out it sends a signal to your car to come back to the door.

I also imagine that cars will no longer be restricted to the right side of the road. Depending on traffic, cars could drive on the left side of the road and easily merge back over if another car was coming. Roads could be optimized for traffic in this way. I imagine it would be like walking on a sidewalk. Other than the occasional dance step that occurs when you start walking towards someone head on, humans can share the same sidewalk going both directions pretty easily.