Traditionally, walking robots require a large degree of sophistication in design and software control. Despite all that, such robots (e.g. Honda's Asimo) can navigate only the easiest of environments, compared to what a three year old child could do. Now, researchers from three universities (Cornell, University of Michigan, and Delft University) have developed robots (designed on passive-dynamic principles) with comparatively simple design, that can walk naturally. The robots were displayed at the annual meeting of the American Association for the Advancement of Science in Washington DC, USA.

Walking Robots (Courtesy: NewScientist)These robots use simple dynamics and motors/sensors/electronics to propel themselves. Their motion is self-correcting, not unlike how a human navigates the terrain. The robots perhaps walk a little like a drunkard, but manage to stay on their two feet, and the walking looks more natural. In that sense, their walking is more like how kids walk. Please click here for the research page, and here and here for two movies from that page.
In addition to more efficient, walking robots, this research can also lead to better prosthetics. The researchers were inspired by mechanical toys that automatically stroll down a slope under gravity. While Asimo uses ten times as energy as a human, these robots use about the same energy as an average person.
Personally, I think the first two robots look a lot like C-3PO and R2-D2 from the StarWars movies!