The multimedia manifesto that Cho Seung-Hui shipped to NBC News, in between rounds of killing, included the digital picture shown above of the Virginia Tech murderer brandishing two pistols. A message about the times is implicit: that the technology for recording horror has advanced, even if the technology for inflicting it has not. The rambling rationalizations, the pictures of hollow-point bullets--Cho's final testament was like a deranged MySpace parody.
From the beginning, the tragedy fit a generation used to living in public through YouTube and social-networking sites. Now members of that generation were killing, dying and mourning in public. When graduate...