IMNSHO, Bullwinkle is right ... actual security is not possible and the airlines/airport/government/police/etc are keenly aware of the fact
BUT, the APPEARANCE of security is of vital importance to the viability of the airline industry ... as much as making the skies safe, making potential passengers BELIEVE they're safe (and willing to buy a ticket) is what is actually being accomplished ...
But again, IMNSHO, the next incident is not likely to come from that direction ... terrorists know now that passengers on airplanes will no longer be peacefully herded to the back of the plane ... one of their 9/11 objectives (perhaps one even more significant than the WTC) was foiled because passengers knew the old maxim of compliance with the hijackers was not the path to safety ...
Surprise and shock are key elements of what makes terrorism effective ... their airplane card's been played ... their next move will be one that we've not anticipated or prepared for ... so, I don't give a big pink s**t if it's called 'profiling' ... call it what you like, but if our government, our police or we individually are to foil the next attempt, we need to be alert to unusual and suspicious activity and quick to act ... period.