It looks a lot like the midday break at some elite college campus. But almost 12 years after it was launched by precocious Stanford grad students Larry Page and Sergey Brin, Google and its founders are grappling with a very grownup set of problems. Google's core business, online search, is slowing. That is partly due to Google's own success; it's hard to keep posting record growth rates when you dominate a business so thoroughly -- Google sites lead the U.S. market with 64% of all searches conducted. But more crucially, the web has changed significantly since Google became a verb. There is (at long last) fresh competition from Microsoft's Bing, and also a new wave of sites and services that offer alternatives for consumers' time and attention -- and the advertisers that follow them.