Jeanna Barrett had spent the last 20 months in Seattle helping grow a location-based mobile app. In April 2011, Groupon acquired the startup, and it declined to keep her on staff. "I called my parents after I found out I didn’t have a job at Groupon and said, 'I'm moving to San Francisco.' I just knew I wanted to make it work," Barrett said. Barrett is one of thousands of hungry tech workers that move to San Francisco each year.