Post 9/11, post the Shoe Bomber and and post, for want of a better description, the Pants Bomber I've had to travel to the United States in the aftermath of a security incident and have had the dubious privilege of witnessing at first hand the incrementally heightened security procedures that have been put in place. Witnessed as a passenger I might add, so I can only pass comment on what I've seen and not what may or may not be going on hidden behind the scenes and out of site of me and my fellow passengers.
Even pre 9/11, airport and airline security seemed to rely on a degree of ritual, of knowing the right incantations and of knowing the right answer to give to certain key questions; "is this your bag?", "did you pack it yourself?", "could anyone have tampered with your luggage?" and "has anyone given you anything to carry?". Answer the previous questions with "yes, yes, no, no" and you would be granted the honour of being able to check in and pass to the mysterious land of "airside". Answer them incorrectly or get the yes's and no's in the wrong order and your life would become very interesting.
At Heathrow yesterday morning, prior to getting on my (much delayed) flight to San Francisco, I remembered to give the aforementioned answers in the right order (this is critical to success), took off my belt and shoes, took my laptop out of my bag, put the whole lot in large grey plastic trays and while they passed through the x-ray machine, I passed through the metal detector with nary a beep.