'The bot, named "Cubli", contains three internal wheels that spin faster or slower to give it the momentum to remain balanced, even if the surface it sits on becomes tilted. They can also be abruptly halted to give the cube the oomph to jump up to a balanced position from flat on the surface.
'The principles are similar to those used in satellites to stabilise them in orbit, so they don't end up spinning around uselessly. It's thought the technique could also be used to build robots that are able to explore other planets, or self-assemble.' (Wired article).