Fast-growing Pinterest has moved its headquarters to San Francisco, near games giant Zynga and online room-rental service Airbnb. The pinboard site isn't talking about its growth plans, but the San Francisco Chronicle reports the company is leasing part of a 48,000-square-foot building at 808 Brannan St. It also says rents are more favorable in the South of Market area, averaging $50 per square foot, compared with $75 per square foot in downtown Palo Alto. Since launching in January 2010, Pinterest has amassed more than 20 million monthly visitors. An Experian Marketing Services report ranked it as the third-most-visited site after Facebook and Twitter. And pointing to the flow of executives from Google to Facebook to Pinterest, Sarah Lacey at Pando Daily recently suggested that the site might be the hottest place to work these days. The company reported just 20 employees in March, but listed 31 workers on its website Tuesday. It's looking for a product designer as well as five engineers positions, including search and data mining, front-end engineer, iOS engineer, site reliability and software engineer. Related Links Pinterest leaves Palo Alto for San Francisco [SiliconValley.com] Pinterest moves to San Francisco from Palo Alto [SF Chronicle] The All-Important Valley Talent Flow: Why I Suddenly Just Got a Lot More Interested in Pinterest [Pando Daily]