Could we prevent another Virginia Tech or Columbine with technology?

One tech writer thinks so. Cringely is normally focussed on predicting the next emerging technology, but this week he ponders the case of the Virginia Tech shooter, and compares it with his own experience with an unstable personality in his life. I also have known some people who were clearly unstable and needed care (and largely recieved it), but whom I worry about to this day. It is an interesting question to wonder if it would be possible to create a system to scan the blogs and twitter posts and etc. that people freely post in an attempt to predict when individuals enter dangerous states. Then again, it would also be a dangerous system, like the Pre-Crime of Philip K. Dick's Minority Report, because it would tempt society to act before any crime has been committed. And really, is it possible to have such a system which can act early enough to extend a helping hand, while the disturbed individual is still capable of accepting it?