Researchers create skeleton robot with human-like muscles
From Popular Science and Engadget referencing a Japanese article and video at the Tokyo Institute of Technology:
Researchers at the Tokyo Institute of Technology [gave a robot] human-like muscles to help with movement. The microfilament muscle "tissues" connect to joints and expand/contract just like the real thing. In fact, the robot has the same number of muscles in its legs as we do. At this point, they're not very strong and though the strands help with smoother movements, the skeleton still requires assistance to walk.
Similarly, The Economist has a report on an article in Science on research out of Harvard, which created an artificial sting-ray. The Harvard project also used artificial muscles, feeding them energy from a glucose filled substrate in the surrounding water, although the food source could hypothetically be more convenient in the future.