As with all third party applications, installing is still somewhat difficult. It looks like the latest preinit will make things a bit easier, but you still need to create a filesystem on /dev/hda2 so that empeg-preinit can mount it as /programs0. It's also still in it's infancy, considering that I started working on it less than a month ago. There are installation instruction in the README file in the tarball, I could merge those in the page.

Right now gpsapp doesn't do 'maps', it just shows a route and directions that are grabbed (off-line) from the mapsonus website. The parser that converts the raw route descriptions is a Python script and a bit picky. Once you get it going it isn't too hard to collect a couple of routes. But I consider this method a dead-end anyways, mapsonus could remove the raw route download functionality or change the format arbitrarily. So I would like to add on-line routing at some point, probably based off of the tiger/line datasets.

I've already looked at those a bit and they are quite amusing, no one-way street information and it doesn't know about bridges and such. So, combined with my knowledge about routing algorithms (i.e. none), it definitely gives some really interesting routes that can sometimes be challenging to drive Right now I feel like I'm reinventing a bunch of wheels, and the remaining parts of car, trying to figure out how to store and index the dataset in such a way that it is actually usable for mapping, routing and possibly geo-locatiing (i.e. give an address get a coordinate).

Not sure about the GPS, does it output NMEA? If so, then you just need to figure out the wiring. Otherwise I need to hunt down the parts of gpsd that deal with the earthmate/tripmate protocols.