AlphaDog Proto is the latest in battlefield companion robotics from Boston Dynamics; AlphaDog is descended from the BigDog robot famous for its agility videos.
AlphaDog Proto can carry 400 pounds up to 20 miles, and do it with only one-tenth of the loud buzzing that accompanied BigDog's movements. Take a look at the following video showing AlphaDog.
Thanks to Anthony Boucher's 1951 short story The Quest for Saint Aquin, sf readers have a feeling for what an AlphaDog Proto can do:
He... took his first opportunity to inspect the robass in full light. He admired the fast-plodding, articulated legs, so necessary since roads had degenerated... the side wheels that could be lowered into action if surface conditions permitted; and above all the smooth black mound that housed the electronic brain - the brain that stored commands and data concerning ultimate objectives and made its own decisions on how to fulfill those commands in view of those data...
(Read more about the robass)