I can't deduce from the press releases whether this is for outbound calls only or will accept incoming as well. Inmarsat rates are over $2 per minute, so if you leave your phone on accidentally, you could run up a large bill! I guess you'd have to enable some special type of roaming agreement to use this service - anyone know for sure?
One further query, if the 'picocell' on board runs out of capacity (or simply fails), won't phones automatically try to contact another cell (on the ground) causing potential interference problems (both on board and on the terrestrial network)?