I've been using Geo Setter to geo-tag my photos, using a GPX file that have live-recorded my position by a Garmin device. I'm pretty certain that such a feature should be available directly in Lightroom, making it even better and more complete photo softeare.
I think Lighroom should have two GPS metadata fields. One for point taken from and the other for point of interest. Useful for landscape photographers. It would be more relevant when auto filling ilocation fields.