I mentioned above that Dr. Martin Buehler, the brains behind BigDog, is now at Disney. We can expect legged machines from Disney soon. They've played around with this in the past, with Lucky the Dinosaur[1], but Lucky tows a cart whose wheels provide stability. Now that they have the top guy on balance and slip control, Disney's robots should get better.

[1] https://en.wikipedia.org/wiki/Lucky_the_Dinosaur