This is a plugin for Lightroom 4 to look up GPS information for photos. It uses the Sublocation/City/State/Country metadata fields to create an address and then sends that to a geocoding API to get possible GPS locations. If more than one is returned it asks the user which one is the best match.
As always feel free to fork. This project is MPL2 licensed. The issues list contains all the things I know I want to fix, if you have other ideas then let's talk.