After a couple of years of painful attempts to geotag all my photos, I've finally got something that might end up working: a small hack that grabs the current location from Google Earth and updates the selected images within Aperture (3.1). This post explains it, and how to install it.
EXIF/IPTC/XMP tagging of GPS coordinates, folksonomy tags, and other goodness is a nice idea, but unfortunately, iPhoto and Flickr don't play too well together. Couple this with the fact that any decent support those products now have is not included for photos already imported into them. So, here are some notes resulting from some experimentation, along with the Perl code I wrote along the way.