TELSTRA Australias NEXTG system will work in flight. On the old CDMA system I had almost continious coverage down the east coast at FL190 with turbo prop speeds and regularly called operations or home.
Easier with a slow aircraft at lower altitude over a built up area than a fast aircraft at high altitude over sparsely populated country. Type of aeriel makes a difference as well, some Australian phones are designed for country use.
Some pilots are using smart phones to log into the MET office radar read out whilst in flight and avoiding the storms.
