http://www.aperturepluggedin.com/2007/08/02/ian-woods-gps2aperture/
don't know how I could live without it. by far the most useful aperture plugin so far. we use gps for all outdoor photoshoots for quite a while, now we can easily see where photos have been taken with a click. also recommended is houdahgeo - getting gps data into the raw files and on google earth tracks.