https://github.com/inmcm/micropyGPS
This is small and easy to use parser for NMEA navigation sentences used on many GPS receivers modules. The github page has a much more extensive explanation and usage examples.
This was developed in conjunction my MTK33X9 chip set command generator: https://github.com/inmcm/MTK_commands
The original discussion (with some development notes) is here: http://forum.micropython.org/viewtopic.php?f=5&t=452