With the new iphone app to send destinations to the Z110BT, it should be possible for any device to send destinations to the unit. We just need to figure out the protocol the app uses to communicate with the unit.
With that information, a java midlet could be created, so most phones can send destinations to the unit. Both from geotagged images, but also from other sources, like internet, contacts, textmessages, etc.
I am guessing the protocol is a simple one, based on the bluetooth serial profile. I don't have an iphone, so I can't even test the app.