At about 9 a.m. Thursday, three-time Amgen Tour of California winner Levi Leipheimer announced via a "tweet" that he was going to defend his title in 2010. It was part of a high-profile Twitter conversation started by Gov. Arnold Schwarzenegger that went something like this: "@schwarzenegger: Great news for American cycling fans and CA. The 2010 Amgen Tour of California will be better than ever. @lancearmstrong will you join us? @lancearmstrong: Absolutely! @schwarzenegger, I've decided to ride the #Amgen Tour of California in 2010. Can't wait. What about you @levileipheimer? @levileipheimer: I'll definitely be racing the 2010 Amgen Tour of California, defending my title." Then at 4:30