Geotagging also known as geocoding is a process of adding geographical information to a Blog, Photo , Video, RSS feed or any other data or info. This can be used by variious programmes to show the info. in a map interface making it easier to locate info. whiich may be of interest to user. For example if you want to read blogs on India Australian Cricket Match then type Perth or locate Perth in the Map and most probably you will get info on subject of your interest by those who are close to the action.
Currently Flickr has 5% of its Photos tagged. Imagine if all the photos are tagged. It wil create a database of visual info which may be combined and seggregated by the next Symantic Web and create a user generated Encyclopedia which could beat Wiki. If there is a system of grading bloggers , than a real Time Wiki could be created in which you always get the live info and articles on all topic the day the event happens instead of once a year Brittanica and Encarta gives a limited info.