The NY Times has a long and relatively interesting article on geotagging images and mapping. It primarily discusses Flickr and, to a lesser degree, Google Earth and Picasa and other services such as TripTracker. The article also goes into the geocoding/tagging technology itself. Not discussed in the article is Microsoft's "Photosynth," which is an interesting hypothetical application and extension of all this technology.
Mapping, images (including video) and local/travel are rapidly coming together in very rich applications, as alternatives to pure text-based online navigation.