In this photo taken Thursday, May 3, 2012, people walk along Market Street past the lobby of a vacant office building by Twitter's new headquarters in San Francisco. With Twitter?s new headquarters set to open there soon, residents of a San Francisco neighborhood notorious for crime, drugs and homelessness remain among the least likely to have any way to send a tweet, much less access to basic goods and services. At a recent weekend ?hackathon,? engineers and entrepreneurs sought ways to use tech to help people in the Tenderloin and Mid-Market Street area find food, housing, healthcare and jobs. In the process, city leaders hope to ease tensions between needy locals and newly arriving startups flush with cash. (AP Photo/Eric Risberg)