Are you sure the camera app built into your phone won't already do that? Mine will (but I can't remember whether the default was to have geotagging off, or on).
ETA: you're on iPhone, yes? Unless you're on a very old OS, you do have geotagging, you just can't turn it on and off separate from all the other location services on your phone. Supposedly iOS 4 allows restricted location services.
http://www.jackleblond.com/iphone-ph...childern-play/