As I compose this post, I'm sitting near Anchor Bay on the Island of Malta...Popeye Village, to be exact (see pg 68, Shutterbug May 2005). I travel internationally, so I have had plenty of experience with airport security and screening in various countries, but mostly Europe & Asia.
As you may be aware, when checking baggage, at least in the U.S., baggage screeners will ask you if you have film in your bags.... if so it must be removed before being X-ray'd. The newer screening machines (at the larger airports, like Chicago) are very powerful...so be sure to take your film out! In fact, it's easier to put your film in your carry-on bags, or better, a detachable pouch on your carry-on bags. Simply put it the handy basket for your keys & change. No sweat!! On that note, since I carry a Nikon 8700 Coolpix, I usually have an abundance of CompactFlash cards. These I also put in the keys/change basket.... I haven't had x-rays disable one yet, but I'm not taking chances. In my profession, I work with microwaves, x-rays, and all sorts of electro-magnetic fields -- trust me, these cards do become unstable!
Next up -- what to carry your precious cargo in? I have a small Lowepro bag, since I do not have any extra lenses or flashes yet. I had orginally attached this to my backpack, figuring I would have easy access. A good idea, but it needed some work. This made my pack too big to fit in the overhead compartments, except in the 767 & 777. Another consideration --- on puddle jumpers, my pack is too big, and must be checked... now I carry sensitive information, as part of my job -- so now I have to choose, does my pack get checked planeside, or my camera? I'm sure you have seen how most baggage gets treated... the thought of my camera getting stuffed under the plane is very unsettling. The solution? Arrange your carry-on bags so you can fit your camera inside of it -- Tenba, Lowepro, & others have great systems for this, and the cost is negligible, compared to replacing your camera.
Carry lens wipes too! I learned this after visiting our esteemed Dallas Airport. The FSA who checked my carry-on bag took everything apart -- I mean everything, including my camera. What I didn't realize, however, is that he'd put large, oily smudges on my screen, viewfinder, and lens! Here I was, 50,000 feet over Nova Scotia glaciers and ice caps, and I have to take the time to clean the lens first!
In most foreign airports I have come to, security screeners will only give a glance at laptops, but cameras they may insist are unloaded of film or cards. They may ask you to turn it on (the same holds true for laptops), to be certain you actually have a camera or laptop -- and not something else.
I also have some filters and a small table-top tripod (6")in my camera bag. This has really paid for itself, especially when on approach or in bumpy air, or if you are at great height...the filters for getting truer colors, and the tripod for steadying your shots on an armrest or seatback.
And so ends my monologue! I hope you find my experiences helpful. If I run into anything else exciting, I'll be sure to pass it on!