maemo mapper will act as an interface to google's route planning service,download the maps, plot the route on the map and then give turn by turn directions. i've never used a dedicated satnav system but i think it's pretty cool. it doesn't do it's own route calculations so you have to be online if you want to update your route but if you've got a suitable 3g phone and data plan it can use that to recalculate routes. not perfect but not bad. or does everyone know this already?