Ed and I had the pleasure of flying just after a young Nigerian ignited hs underwear on a flight from Amsterdam to Detroit on Christmas Day. Fortunately since we were flying domestically, we weren't impacted by the TSA's clumsy response (one carry on, no moving or anything in your lap the last hour of the flight, no wi-fi, etc.).
We had braced ourselves for a repeat of the day we flew to Hawaii in 2006, the morning authorities in London apprehended a group planning to use liquid explosives. That day we spent 8 hours in the security lines, 15 hours at the airport, and arrived exhausted and liquid-less, but no safer than any other day.
Bruce Schneier summed up everything I feel about air security and what he calls security theatre in his excellent essay, "Is aviation security mostly for show?" There are so many, many ways to blow things up, so many things to blow up... the meager and misguded tactics we employ to provide "security" absolutely does not prevent all bad things from happening.
Schneier lays out the situation perfectly, but here are a few choice bits:
Our current response to terrorism is a form of "magical thinking." It relies on the idea that we can somehow make ourselves safer by protecting against what the terrorists happened to do last time.
...It's not security theater we need, it's direct appeals to our feelings. The best way to help people feel secure is by acting secure around them. Instead of reacting to terrorism with fear, we -- and our leaders -- need to react with indomitability, the kind of strength shown by President Franklin D. Roosevelt and Prime Minister Winston Churchill during World War II.
By not overreacting, by not responding to movie-plot threats, and by not becoming defensive, we demonstrate the resilience of our society, in our laws, our culture, our freedoms. There is a difference between indomitability and arrogant "bring 'em on" rhetoric. There's a difference between accepting the inherent risk that comes with a free and open society, and hyping the threats.
We should treat terrorists like common criminals and give them all the benefits of true and open justice -- not merely because it demonstrates our indomitability, but because it makes us all safer.
Once a society starts circumventing its own laws, the risks to its future stability are much greater than terrorism.
I highly recommend reading the whole essay here: http://www.cnn.com/2009/OPINION/12/29/schneier.air.travel.security.theater/index.html.
UPDATE: M. mentioned some tag lines for the TSA floating around twitter. The best: "Protecting you from yesterday, tomorrow." Brilliant!