Airports still seem to have hangups about mobile phones being a risk to aviation fuel despite that issue being started by a hoax press release and disproved many times over at least a decade ago. Last year I was spoken to harshly for reading my ebook reader on the tarmac at Newcastle airport. The ground staff asked if I realised there were thousands of gallons of fuel beneath our feet - as if the puny battery of the ebook was going to morph into a huge thermic lance and cut through 2 metres of concrete. They announce that all electronic devices be turned off for take offs and landings because its in the rules but they must know that there are still dozens of devices still active due to passengers not knowing when off is off or just making an error. There were certainly a number of active devices on a recent trip to KL. If they were serious about it they would have to perform some sort of scan. Of course they know it is not an issue but it is in the rules and has to be implemented. Sadly rules get into the book a lot easier than they go out.
Don't want you getting a complex that I'm picking on you Chris

but once again I feel I have to correct some points here.
Firstly, underground fuel tanks.
The fuel tanks below you may be buried below 2m of reinforced concrete, but the vents for these tanks are not. This also goes for the aircraft tanks. As turbine aircraft tanks are filled at rates of up to 1000L per min, the empty space in the tanks (air with fuel vapours) pours out of the vents at the same rate. In our aircraft, that happens to be underneath the wing just where passengers are walking past to board. All electronic devices (whether or not they have a flight mode) are required to be completely switched off when tarmac boarding because 1000L of air with fuel vapours can be pouring out of the tank vents as people walk past. And while jet fuel has a particularly high flash point, it can quite easily be reached in certain circumstances. Other aviation fuels have flash points as low as -43 degrees.
Secondly, you may think your ebook battery might not pose a threat, but lithium batteries pack a MASSIVE punch for their size, and are also prone to thermal runaway in the event they've been damaged (by dropping) or overcharged. See here:
http://www.youtube.com/watch?v=j4DlUUZxFvsNot only are lithium batteries required to be very carefully temperature controlled, their fires can also be very, very difficult to extinguish in the aviation environment. While lithium ion batteries have been a great revelation, their characteristics (thermal runaway and difficulty of extinguishing) combined with the aviation environment means they are less than ideal, and all crew (including flight crew and ground staff) are trained to be cautious of them.
Thirdly, electronic devices are required to be off for takeoff and landing because you can watch as much Mythbusters as you like, electronic devices create EMF which can affect aircraft systems. The VAST majority of aircraft wiring is UNSHIELDED. I will give you two examples of actual events which have occurred to me:
a) Ten years ago, on a night freight flight I was training a new pilot. As we passed over Broome in the pitch black, his phone (which he'd left on by accident) was heard to make the audible da-ding da-ding da-ding through our comms system as it came into coverage. The fairly old, semi-digital autopilot (which had worked for hours without fault) simultaneously and aggressively began an uncommanded roll to the left. As we rolled through 60 degrees of bank towards vertical, I disconnected the autopilot and levelled the aircraft. Once the phone was turned off, the autopilot worked again without fault for the remainder of the flight (and for many months afterwards).
b) Only just recently, on a scheduled passenger flight out of Adelaide, I attempted to engage the new generation, completely digital autopilot on the First Officer's request immediately after takeoff. It refused to engage time after time, and so he was forced to hand fly the aircraft to cruising altitudes through some very ordinary weather. We completed our checklists and troubleshooting to no avail. When completing the announcement to passengers, I requested that because of potential interference, I wanted all electronic devices switched off. Two mins later, the autopilot engaged immediately and continued working for the rest of the flight. It could not be faulted by engineering during post-flight inspection. There is absolutely NO doubt in my mind that an electronic device was interfering with the digital autopilot.
Lastly, I have also have no doubt that devices are sometimes left on either accidentally or intentionally during flight. It is simply false reasoning to suggest this means it is okay for everyone else to do. If you saw someone speeding down a road at twice the limit, would you do the same just because they didn't have a crash?
It is actually a legal requirement that you follow the directions of flight crew (ie the flight attendants who tell you to turn devices off). I know of at least a dozen cases where passengers have actually been charged with a criminal offence for failing to follow the directions of aircrew, and hundreds where passengers have been offloaded before departure and forfeited their fare.
Sorry this has been a big essay, but it really rubs me up the wrong way when people make generalisations in the public forum which could encourage others to do the wrong thing.
You might think the rules are ridiculous, or out-dated, or have been proven wrong by a woefully inadequate one-off test on Mythbusters. But as someone who works in the industry and whose life depends on it day in and day out, I just want to get home safely and see my kids every night... I don't need someone who thinks they know better starting a fire or interfering with my equipment.