As far as broad lessons for risk evaluation and mitigation that we might carry back to the IT security world with us, I think there are a couple lurking in the story.
First, big investments in sophisticated technologies won't catch amateur-hour attacks. It's possible that the propane tanks could have exploded and that would have been pretty serious. The current spin in the media seems to be that this was so boneheaded an attempt that it wouldn't have been likely to hurt anyone. Consensus view is that the guy was an idiot. I'm willing to believe that and I'm glad if he was too much of a rube to pull off the attack. But even goofballs can kill you. And I don't think any of the talking heads saying his bomb was never a real threat will volunteer to sit next to a smoldering car filled with propane tanks. If the propane tanks do blow, it's going to be pretty hot. So, there was danger there, but at the same time it was not the sophisticated sort of attack that we tend to focus on.
Most attacks are in fact low-tech, both in the world of home-rigged explosives and in the confines of the enterprise network. The comparatively cheap investments that give you options for finding or mitigating low-grade attacks are the investments to concentrate on. There are lots of options for sophisticated detection systems that will try to make the extended, real-time correlations that enable you to detect hackers who are trying to fly under the radar. Since this isn't most hackers, you've really got to keep these kinds of investments in perspective.
In Times Square, the low-cost investments had been made and they delivered brilliantly. There were plenty of cops on the street in the normal line of duty. There were lots of cameras to provide after-the-fact forensics (I'm not particularly espousing cameras, mind you -- my point is simply that they cost less than radiation sniffers). And the really straightforward measure of building in cement-block obstacles to prevent someone from driving a car bomb into at least some of the more sensitive buildings was in place (though, as I think about walking though the square, it occurs to me that there's probably opportunity to improve the protection of storefronts and subway entrances--if we're going to react directly to the attack with security investments, this is surely the best bang for the buck).
Another lesson: fast, old-school detective work creates fast results in catching culprits, thereby creating at least some measure of deterrence. The police closed in on the alleged attacker quickly and snatched him up before he could flee the country. This business about the no-fly list is a red herring. The point is they new how to do the basics, like track the VIN number on the Pathfinder. Basic "create the timeline using filestamps and log files" sort of work remains a skillset that every IT security team should have.
There are still plenty of sophisticated attacks and attackers, probably a lot more-so in the computer world than in the physical security environment. You can't ignore them, but you probably can't stop them during the attack, pretty much no matter what any vendor tells you about automated response. But what you can do is assemble better monitoring tools and better analysis tools and watch for anomalies that would signal that something was up. This is where we should spend the money in anti-terrorism, I'd wager, but I know less about that. I'm quite sure it's where investments are warranted in network environments, because normal parameters are easier to spell out and easier to check and recheck for exceptions.
Robert Richardson directs content and programs at the Computer Security Institute -- gocsi.com.