The Carnegie Mellon snake robot has an amazing number of different gaits and motions: Linear Progression, Sidewinding, Rolling, Swimming, Channel Climbing, Pipe/Tube Climbing, Pole Climbing, Cornering, and Pipe Rolling.
The amazing capabilities of the CMU snake robot makes me think of the robot snake spy from Greg Bear's excellent recent novel Mariposa. In the story, the snake robot spy is released a significant distance away from its target; it must successfully navigate all the way to its rendezvous with an agent.
Greg Bear's fictional snake robot does have a few features that the CMU snakebot lacks:
The coil on the table appeared to be a snake - tan and brown with black specks and a spade-shaped head. It did not look alive and it did not look dead.
...He reached down and partially uncoiled the snake, then squeezed its middle. A small hatch popped open, giving a glimpse of gleaming steel ribs and wires. He placed the tube inside the snake, then closed the hatch.
"The snake has hi-res terrain mapping tied in with augmented GPS, and in this model, face and voice recognition... Within sight of a targeted individual - I mean, the intended individual - it will make an audible announcement and open its hatch."