The right answer is an interchange format like shapefile, but I can't comment on how far Jan has gotten with his testing or whether he was using python.

My opinion is gpsapp should support an interchange format, and someone else gets to write the gdf to interchange format translator. I think shapefile, the de fecto vector standard of the GIS world, should be that format, but to be honest I haven't ochecked to see if things like street direction can be represented. Perhaps I should.

Someone want to write a gdf parser?