I have put posting about this, but I guess it's time to say a few words.
The VT attackwas a terrible event, and my heart goes out to the friends and families of the victims, and to anyone deeply affected by the tragedy.
From what I have read, it appears that the attacker may have been paranoid schizophrenic. Though there were mistakes that were made, it is understandable that the attacker was able to get away with this violence. No one really understood the threat he represented. Any responsible person who had known what Cho was going to do would surely have stopped him.
It's natural for us to look for some course of action that would prevent this sort of thing from happening in the future. The gun lobby and the gun control lobby have both been milking this story as a PR vehicle. The authoritarians want to ban video games, books and movies. The supernaturalists want to blame it on materialism. Early commentators blamed it on muslims or remarked on the value the tragedy would have to terrorists. All very bad form in my opinion.
The way to prevent these things is to look for signs of mental illness, and treat those signs as an extremely serious matter. We can improve security procedures somewhat, but we're not going to give up our freedoms and our way of life in the process.