As sites like Wikipedia inform us, geotagging is the process of adding geographical or location information into media, such as digital images or videos (or basically any entity: it is wide field). While we are currently looking into linking various games related tools and processes with the social media initiatives in our pervasive gaming research (read: within IPerG), I am also interested in the simplest possible way of making location tagging available for large audiences. While there are also developments of building GPS into digital cameras, and software tools for automatic location tagging with GSM cell data (in cameraphones), I still think that the approach of Flickr Maps is probably going to be most popular by short range, at least. It is so easy to drag your photo into certain location in the world map, and also browse photos with the same intuitive map interface. Example: link to few images I have mapped in my Flickr Map. (I think you need to zoom out a bit in order to actually see any of them, though.)
frans goes blog 
Speaking about “geotagging”: do you know locr?
locr offers the ideal solution and makes geotagging exceptionally easy. locr uses GoogleMaps with detailed maps and high-resolution satellite images. To geotag your photos just enter address, let locr search, fine-tune the marker, accept position, and done! If you don’t know the exact address simply use drag&drop to set the position.
For automatic geotagging you need a datalog GPS receiver in additon to your digital camera. The GPS receiver data and the digital camera data is then automatically linked together by the locr software. All information will be written into the EXIF header.
In the standard view, locr shows the photo itself, plus the place it was taken. If you want to know more about the place where the photo was taken, just have at look at the Wikipedia articles which are also automatically assigned to the picture.
Have a look at http://www.locr.com.