Honda on Wednesday unveiled the U3-X, a stool with a unique directional wheel system that allows it to travel diagonally, as well as right, left, forward, and backward. It's basically a robotic unicycle. The device is able to readjust itself so that instead of riders having to constantly balance themselves, the robotic unicycle does the compensating.
If they can figure out how to keep that balance with a bipedal configuration, BAM one step close to robot legs. It'll be a risky procedure, but I think it'll be worth it.
I'm thinking that the thing has a weight limit. Plus, it might be useful for people who're recovering and can walk but can't do much else yet or walk for a long time. Besides, it's not blindingly fast so walking will still have merit, even if it is just for the sake of speed.