I wish I'd discovered this before I went to China! Obviously it's good to have geo-tagging with the camera, as with the A77, but it uses lots of battery (lots) and isn't always that fantastic.
I just discovered gps4cam - an iPhone app for geotagging photos.
What a neat idea!
it uses the GPS info from the phone (and the date and time if you want as well).
You simply Start a Trip, and the phone grabs a gps reading at intervals you specify. When you finish the trip, a bar code is shown on the phone, and you snap that with your camera(s). Then use their desktop import routine and the program tags the files with the correct GPS data . .. how cool is that!
(now everybody can tell me they've ben using it for ages