It might take them a good 92 hours longer than the fastest human runners, but a group of five pint-sized humanoids have officially embarked on the world's first full-length robot marathon. The Robo Mara Full, put on by Japanese robotics company Vstone, kicked off today in Osaka, Japan, and will see the mechanized competitors through a 42 kilometer (26 mile) race, estimated to last at least four days. During the marathon, entrants will circle a 100-meter indoor track a total of 422 times with little help from their human coaches -- contact is only permitted during battery and servo replacement. Vstone's
