Nice link G...
I've been working on my own device which boils down to a data logger with a gps and an XBee attached, so I've been following this thread with some interest as well.
I've also found these links to other GPS loggers to be interesting:
http://hackedgadgets.com/2008/11/30/gps-data-logger-using-an-sd-card/
http://www.gedanken.demon.co.uk/gps-sd-logger/ (the completed unit picture seems to be missing now)
At any rate, here's some more food for thought.
Brad.