Being able to control all aspects of the CDMA (Verizon) version of the iPhone would be ideal. I like being able to tweak things. If you find out that the jailbroken phone allows access to such control, that's one option.
But not everyone is comfortable with hacking expensive phones. So for them, being able to enable/disable Airplane Mode from within Gaia GPS, as opposed to having to exit the program, go to Settings, make the change, then go back into Gaia GPS, get a fix, then exit the program, and go back to Settings every time they want to get a fix would be a boon.