Boston Dynamics has developed a quadruped rough terrain robot that they call "Big Dog." It's about the size of a big dog (clever naming, eh?) and can carry a 120 lb load, trot at 3.3 mph, and climb a 35 degree slope. This video shows Big Dog in operation. It's especially impressive when it's kicked and recovers its balance. The robot is hydraulically actuated and is powered by a gasoline engine.
Possible uses? (besides trotting along behind me carrying my stuff when I'm backpacking - although they'll have to do something about the noise!).