Forgive me if this is an ignorant reply, but I thought the point of this was to give developers the ability to make official, Apple-approved apps that interface

Forgive me if this is an ignorant reply, but I thought the point of this was to give developers the ability to make official, Apple-approved apps that interface with devices that communicate across serial. Things like industrial machinery, GPS loggers etc. I've actually been looking around for something like this in order to make an iPhone application to use as a flight computer with gliders, since all glider-approved GPS loggers (which are MUCH more accurate than the iPhone's built-in GPS) communicate via a serial connection. If I understand correctly, until now you would have to use a jailbroken iPhone in order to do this? Is there an easy way you can use Bluetooth to solve the same problem? Please correct me if I'm missing something here.