Thanks Marc Andreessen for posting this. Way too cool, it's like cutting an earthworm in half, but not only does it keep on living, it pieces itself back together again.
Here is a great reason as to why I check out Metacool's blog on a regular basis. This is a rad video of Boston Dynamics Big Dog (I would recommend turning off the sound, all you hear is the annoying buzz of the motors). The ability for it to respond to factors in its environment that are out of its control is amazing. Enjoy.