Usain Bolt of Jamaica won his second straight Olympic gold medal in the men's 100 meters today, crossing the line in an Olympic-record 9.63 seconds. Bolt joined Carl Lewis as only the second man to go back-to-back in track's biggest race. Bolt's training partner and fellow Jamaican, Yohan Blake, finished second in 9.75. American Justin Gatlin took bronze in 9.79.
In other Olympics racing news, double-amputee runner Oscar Pistorius failed to reach the final of the 400 meters today, following up a bad start with a slow race and finishing last in his semifinal heat. The first amputee to compete in track at the Olympics never stood a chance and finished the race on his fiber carbon blades in 46.54 seconds, .95 of a second behind winner Kirani James of Grenada. Pistorius is still expected to run the 4x400 relays, which start Thursday. (Read more Usain Bolt stories.)