Should navigation info be gratis? Well, perhaps. There are arguments to make both ways, and since it seems that people are willing to pay for it, that's a good indication that it will likely remain a pay service in the near future. Then again, the streets are open to everyone who pays their taxes and registration, and that should probably include maps and directions - the information side of the upkeep.
Should navigation info be libre? There's no reason to keep it locked up in my opinion.
Online map services like Google Maps and whereis.com tend to be gratis but not libre. That is, they're no-cost to use, but they're a bit locked up. If you could get access to either one while on the road and had a GPS receiver, you wouldn't need a dedicated navigation device.
Mokalus of Borg
PS - I don't think that particular application is far off.
PPS - As the internet's reach grows, offline applications will be less necessary.