From the report on Radio 4 my understanding is, as VnV2178B states, that effectively the radio mast is placed within the aircraft so the mobiles only have to communicate a short distant, and therefore operate at low power. It said that this way all the signals would be kept within the plane, hence frying all the passengers!
However the guy from Ofcom was also asked about the irritation factor and he did have the decency to say that using the phone for email or texting shouldn't annoy neighbouring passengers. Presumably implying that the ability for passengers to use mobiles is going to be hellishly irritating to those that don;t want to use them!
If they can work safely I'd like to see either an area within the aircraft dedicated for making calls, or for calls to be barred and only email/textx to be used with the phone on silent to stop annoying beeps!