With 31.9 million global users in May, the 5-year-old startup has become the object of marketer affection and now boasts a $1.5 billion valuation. Some would argue that Pinterest is now the No. 3 platform for brands to obsess over, after Facebook and Twitter.
Mr. Silbermann, now Pinterest's CEO, left Google in 2009 to start the service, which is organized around people's desire to collect stuff and show it off. Mr. Sharp, meanwhile, is the design brains. Both declined to be interviewed for this piece -- they're too busy working on the product.