For the last year or so, a designer by the name of Nicholas Felton has been hunkered down at a desk just 15 feet away from Facebook CEO Mark Zuckerberg's. Felton is something of a design superstar -- his stunning layouts chronicling his life have earned him a spot in an exhibit at MoMA -- but in Silicon Valley, his ilk are known as "pixel pushers." Yet Felton's proximity to power is no accident. Facebook is one of the very few Valley companies whose senior management, starting with the CEO, understands design as a sustainable competitive advantage. They're not just responsible for the pixels, Felton says. They're responsible for a lot of the core ideas for how the product works. But describing the company's goal as "designing a plaza" leaves out the biggest idea behind Facebook's design. Facebook doesn't just want to catalyze interactions. It wants to catalyze emotions.