Self-Solving Rubik's Cube
hackaday.com
hackaday.com
One of them also does a "prediction" that allows the spectator to scramble the cube, then check the SMS picture that was sent to them, and it is a picture of the cube as they scrambled it. Lots of variations on the motorized cube theme out there.
Unsurprisingly, the same manufacturers make watches with similar electronic hacks built in.