BigDog @ bostondynamics.com (file under geek).
"The Most Advanced Quadruped Robot on Earth"
"BigDog is the alpha male of the Boston Dynamics family of robots. It is a quadruped robot that walks, runs, and climbs on rough terrain and carries heavy loads. BigDog is powered by a gasoline engine that drives a hydraulic actuation system. BigDog is the size of a large dog or small mule, measuring 1 meter long, 0.7 meters tall and 75 kg weight".
The video on this page is incredible - or there's a copy of it here (11.5MB) if you know how to download from rapidshare.
There's 4 of them at the robtics department at Boston Dynamics.