This link may be of use to you. Have not read it but seems to have some info for open source gps stuff.
http://wiki.openstreetmap.org/index.php/Making_Tracks_with_Homebrew-ware
@TheBrick(Tommy) started
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This link may be of use to you. Have not read it but seems to have some info for open source gps stuff.
http://wiki.openstreetmap.org/index.php/Making_Tracks_with_Homebrew-ware