Kevin Zeits sent in his diy Nikon d200 gps cable and hot shoe gps mount.
Nikon sells it for $150, but has a 3 to 6 month eta. Ok, it's really just a ttl to rs-232 converter with proprietary connectors - but I love tagging photos with gps info. Now if only I could do this for my canon rebel xt. (It would take a firmware hack at the minimum) If you're not blessed with a d200, check out gpsphotolinker.
http://www.hackaday.com/2006/08/21/nikon-d200-gps-adapter/