A gunman entered the headquarters of the Discovery Network on Wednesday, September 1, 2010; he took several hostages, kept them for some time, and was finally killed by police. "As it has with other breaking news events -- the landing of a jet on the Hudson River in 2009, the 2008 massacre in Mumbai -- the story unfolded first in hiccupping fits and starts on Twitter." "Within minutes, there were photos, including an astonishing one of a man clad in shorts, carrying a rifle and stalking through