There has never been a confirmed case of a cell phone sparking a fire at a gas pump. This urban legend came about because of two incidents (in Japan, I believe) in which a cell phone was suspected to be the ignition source, but it was not proven. The warnings you see on gas pumps are not as a result of any established science, unless you consider lawyers scientists. I would not hesitate to use a cell phone at a gas station.
The most likely culprit, as someone mentioned, is people sliding in and out of their cars and enough creating static electricity to ignite the gas vapors around the fill spout of the vehicle. And, yes, this has happened to more women than men because, again as someone mentioned, many women do not stand outside to monitor the refueling, but like to sit in their cars.
Static discharge, yes, cell phones, no:
http://www.discovery.com/tv-shows/mythbusters/videos/cell-phone-gas-station-minimyth/
Thanks for the input.
More bad science from the liberals who bother us and lie to us.
Of course if your lithium battery in your phone or whatever blows up, that could cause a problem.