Tim,Here's a forum link to some info on the Nav hack.
zerothread?id=133024
I haven't done this but have read many of the posts on the topic. As for mounting, that's a problem considering the mount for the TuneCenter. I think there is a remote for it. But as a concept, the TuneCenterand the Nav hack should allow for visual info from the TuneCenter.
This would not allow iPod control through the cars standard audio controls. You'd still have to push the buttons on the iPod or use a remote to the iPod.