The challenge we often face is how to deal with very aberrant behavior. The reality of the late 20th and early 21st century is that technology has given individuals far more ability to impact others than in the past (although these sprees are actually in decline). I am, of course, speaking of Aurora.
I don't know anything about the perpetrator except that we will find him to be insane. By society's definition, anyone who shoots up a theater full of people is crazy. I tend to see this and other kinds of situations as represented by a bell curve--that our policies and our social science can address people who are in the big middle of the curve, but it is hard/impossible to design policies that hit people who are outside the 95% or outside the 99%.
There seem to be two obvious approaches: improve our mental health care "system" and reduce the damage that such flawed people can do. If we can get people who have significant mental problems the help they need, this would reduce (although not eliminate) the number of situations like these. I am not sure how the new health care legislation will affect the provision of mental health care, but I am hoping that events like this might lead people to consider more investment in this side of health care. Not just to prevent mass murder but to help those who are having problems.
The second strategy, which is politically unlikely, is to reduce the damage a damaged person can do. By this, I mean, of course, gun control. No, we cannot eliminate guns, but it would seem to me that we ought to be able to limit guns that are designed to kill large numbers of people very quickly. I understand that the 2nd amendment is aimed at providing civilians with the ability to counter-act a repressive state, but if assault rifles are justified by the second amendment then so are mortars, anti-aircraft weapons, landmines, armored vehicles and so on. While I would love to see really significant gun control, I understand it is not going to happen. I have lowered my sites (pun intended) to focus just on reducing the speed at which one can fire bullets. If all you have are guns that can shoot six bullets, then you can only hurt six people at a time. I am just thinking of reducing, not eliminating, the damage any deranged person can do.
Of course, the guns and their 30 bullet magazines are out there, and no gun control measure will eliminate those. But it would be nice if we could make it harder, rather than easier, to kill and injure dozens of people in a few minutes, wouldn't it?
We cannot eliminate the tails under any bell curve, but we can do more to help those on the margins and we can do more to limit the damage done by those who slip past. Or not.