J. Domburg has posted a fantastic looking article on getting GPS onto his GP2X, heres an excerpt:
Intro
The GP2X is an handheld running Linux. It has 2 arm-processors and a few peripherial interfaces: Available on the ext-port is a serial port which normally is used as a debugging port. Other hardware can be connected to it too, though. I've used it to build a GPS-receiver into the GP2X, while keeping the original debugging-function.
The beginning
It all started when I saw a SDIO-GPS-card in the sale-basket of a local computerstore. The beastie was only E49,-, which isn't too expensive, and it came with an internal antenna and an external antenna with 5M coax-cable. Even if the device itself wasn't usable, I always would have 2 nice GPS-antennas.
Check out the awesome article HERE