Christine Maddela, the weekend anchor at WKRN-TV in Nashville, joined Twitter on July 1, 2009. It took her all of three days to discover the microblogging service’s potential impact on journalism. “Three days later, on July 4, Steve McNair was murdered, and I broke the news of McNair’s death on Twitter,” Maddela told me during a phone conversation this week. “I was getting this information in, and I confirmed it. We were not on the air at that point and not breaking into programming, and I said, ‘People want to know about this,’ so I did it.”