Today (16.08.2009), during 12th IAAF World Championships in Athletics Berlin 2009, Usain Bolt will try to break his own world record in 100 m race. The final race is scheduled 21:35 (local time). To the final race have been qualified: Tyson Gay (9.77s 22.8959 mph), Usain Bolt (9.79s 22.8492 mph), Asafa Powell (9.88s 22.6412 mph), Daniel Bailey (9.91s 22.5725 mph), Michael Rodgers (9.94s 22.5045 mph), Richard Thompson (10.01s 22.347 mph), Darvis Patton (10.02s 22.3246 mph). (In the parenthesis: semi-final time and average speed)

Jamaican sprinter Usain Bolt is the fastest man in the world. His average speed during the fastest 200 m race so far, during Olympic Games Beijing 2008 was 23.1807mph (click on the link to get speed conversion to other units km/h, m/s, yd/s). He ran 200 meters in 19.30 seconds. Usain Bolt is also 100 meters race record holder. He ran this distance in 9.69s (Usain Bolt mph: 23.085). Note, the average speed in 200 meters race is faster then in 100 meters race.

Update.
Usain Bolt broke his own record in 100m. He ran 100 meters in 9.58s !!!. His average speed was 10.4384 m/s (23.35 mph)

Usain Bolt results and speeds at Berlin 2009
(follow links in the table to get speed conversion):