The New York Times has an article on geotagging, which is a good introduction to the topic and what technology currently exists to implement it. It seems that we are just a few years away from having GPS devices pre-installed in all our cameras (the new chips just cost $4 a pop).
Having recently spent a some time trying to dig through photo archives, I can easily see the advantage of having photos searchable via a map. Looking for pictures from your fieldsite? Just look it up on Google Earth!
There are, of course, privacy concerns. It is hard to keep an informant’s identity secret if the photo you have of their dog shows their exact address. But then, a lot of anthropological practices concerning keeping informants identities under wraps need rethinking in the digital age. It has never been particularly hard to track down an informant if one was sufficiently motivated. Now Google makes it that much easier.
If you really want to get freaked out about privacy issues … the technology already exists to identify the same people across multiple photos, by matching their faces. One could presumably have a map which traces one person’s movements around the world from all the public photos in which she appears.
Makes you think twice about what “informed consent” means when you start thinking about it…
On a related note, you might wish to read Ethan Zuckerman’s description of Hasan Elahi, a conceptual artist whose decided to post his every movement (along with photos) so that the FBI won’t think he’s a terrorist.