CEO and co-founder, Uber
Wanna get somewhere über-fast? Kalanick is banking on it: His hyper-hot app-based car service summons a sedan with the push of a button. The service, which costs more than a cab but saves you the hassle of hailing one, is posting 25% to 30% revenue growth, monthly. And with ambitions to expand to 100 cities around the world (from its current 17) by the end of next year, don't expect it to hit the brakes soon.
Who are 2012's young business stars? We've got the CEO of a blue-chip beer brand, an airline CEO who just placed the largest order in commercial aviation history, and Warren Buffett's new prodigy, among the Silicon Valley hotshots and others.