Tweets from inside Fort Hood were used in news reports about the shooting there last week. But some of the tweets turned out to detail false information. Paul Carr, columnist for TechCrunch and author of Bringing Nothing To The Party, and Jeff Jarvis, professor at the CUNY Graduate School of Journalism and author of the blog BuzzMachine.com, discuss the role of 'citizen journalists' and the line between constructive and destructive uses of social media.