If you haven’t kept close tabs on Usain Bolt, the breakout star of Beijing, since 2008, here’s a recap: the 6 ft. 5 in. Jamaican sprinter set new world records in 2009, running the 100-m race in 9.58 sec. at the world championships and the 200 in 19.19. The Jamaican government gave him one of the country’s highest national honors, the Order of Jamaica, and the diplomatic title Ambassador at Large — he’s Dr. the Honorable Ambassador Usain Bolt, OJ to you. A false start at the 2011 world championships cost him another gold in the 100. But in London, don’t bet against Bolt, now 25, breaking more speed barriers.