Boston Dynamics has been working on various mobile robots for DARPA and others for the past several years. They are getting quite good at it too, and when I say "good" I mean good at evoking something that gives me the willies.
The following video shows the bipedal "Atlas" walking/stumbling around outside in the snow, picking up and stacking boxes and (in a typical Boston Dynamics ploy) being harassed by a human with a stick. One hopes these beasties are thoroughly programmed to not to hit back.
One one level, what the Atlas robot is doing appears pretty simple, and yet when you think of the balance, motor control (literal motors in this case) and decision-making involved, it's quite involved and impressive.
The creepiest thing for me though, oddly, was when it opened the door to walk outside - it just looked so much like a regular person opening the door.