Chris writes -
This page describes the steps I went through in my project to connect a Garmin eTrex Summit GPS device to a Nikon D200 camera body in order to record location information in the EXIF data of images captured using the setup. While this procedure worked fine for me, I do not take any responsibility for you or your equipment should you try this yourself.
Chris Harrison - GPS Project - [via] Link.
http://blog.makezine.com/archive/2007/05/diy_camera_gps_project_fo.html