I haven't tried this app yet (my N900 is still being shipped ), but it sounds awesome. I think you should try to add wifi positioning in the event you can't get a GPS fix. Skyhook is one company that provides the service, and I know Firefox will use wifi to determine position on a laptop if a website asks for it. Basically, the devices compares the available wifi networks in the area to a database, and can usually get a position within 200yards. By no means perfect, but better than nothing!