AKA Geocoding, AKA GPS Photo Tagging, AKA I'm not sure what we're officially calling this yet, is the method of using GPS (global positioning) to Tag images with location specific meta-information. Software for iPhoto and linking to Google Earth here, and more options including Flickr and Aperture here. via TUAW.
UPDATE: Review of GiSTEQ, a device that syncs to your camera's clock and records you location for three weeks. via engadget.