From next year in Europe we could start to see cellphone use on board aircraft. The UK regulator
Ofcom have published their recommendations, but this still needs to be given licensed bandwidth on a European basis, by the EU Radio Spectrum Committee. The approved system involves use of an on-board GSM 1800 Mhz picocell that can be switched on above 3000m. Backhaul is via satellite back to equipment on the ground that will interconnect with the PSTN.
Presumably this will turn into an attractive source of "roaming" revenue for airlines. In their report Ofcom acknowledge that it could be annoying and disruptive with people using phones on board extensively, but say this is an issue for the airline service providers to deal with.