In 2009, DARPA launched the Network Challenge to explore the roles the Internet and social networking play in the timely communication, wide-area team-building, and urgent mobilization required to solve broad-scope, time-critical problems. The challenge was to be the first to locate 10 moored, 8-foot, red weather balloons at 10 random locations in the continental United States. A team from MIT won by locating all balloons in under 9 hours. We helped analyze the factors behind the team's success. We then quantified the limits of this kind of mobilization, and introduced techniques for improving information verification in mass collaboration.