T-Mobile UK has service in dedicated bays in 100 Texaco stations near major UK roads: The deal could ultimately result is as many as 1,400 company-owned Texaco stations having T-Mobile UK service, but a limiting factor is dedicated parking space for motorists using the service. There's an undertone in The Register article and press releases about not just backing up the pump lines (a problem for a gas station), but causing explosions.
The risk of an explosion with a cell phone in a gas station appears to be from the inadvertent seepage of fumes in some cases which can be ignited by electrical activity in a cell phone. The adjacency has to be pretty high. A laptop operating away from the pumps has no risk.
Estonia pioneered gas station Wi-Fi, while a deal with Circle K in the U.S. (which have gas at some locations) appears to have evaporated after Circle K changed hands.