I just got off the phone with Casio on the exact same topic.

Answer: "uh.... I dunno. You sync your PC with it."

"Yah I know. BUT, can I use it to attach a Serial based GPS unit to?"

Answer: "Um.... no. You have to use a CF GPS unit."

I then went to Google and found a bunch of 'em that work with the PocketPC's through the serial connection.

http://www.travroute.com/products/gps/pocketcp/casio.html

http://www.teletype.com/pages/gps/compatibility.html

Does anyone know if MiniStumbler and NetStumbler are compatible with these (or more)?

-Mc