Having worked at gas stations and apron bowzers, I like to pay attention to ignition source issues. While I'm not aware of the issues surrounding normal radiation from cellphones, I worry when they are in use, in oft clumsy hands around any refuelling area.
My understanding is that as long as the cellphone is switched on, there is a potential difference between the battery and the phone itself. Not a big deal when the battery nodes are in contact with the nodes of the phone itself but when the two are seperated, a momentary arc occurs. Seeing as fumes tend to sink and phone-battery seperation often occurs after being dropped onto the ground, this gives a coinsidence of spare voltage and fuel vapour. Perfect grounds to ban their usage around refuelling areas.
Guess this could apply to any portable electric device but cellphones are the most 'accessable' and are therefore most likely to be dropped.
From time to time I see people talking on their phones in refuelling areas on aprons and wonder at their suitablilty for this field.