Microsoft recently released a new application called 'Pro Photo Tools' that allows you to edit the metadata (such as: location, description, date/time, etc.) in digital photographs. Some of this data is automatically added by the camera, the rest you need to add yourself.
Excerpt from the Microsoft site: "The Pro Photo Tools allow you to add, change, and delete common metadata properties for digital photographs. You can place photos on the Live Earth map and then drag them to the right location. The GPS information will be stored back into the photos. If you have a GPS device, can load track route files from the most popular formats (NMEA, GPX, and KML) and see them on the map. Then you can place your photos on the track route. Again, the GPS info will be stored into your file. When you have the right GPS location for your photos, you can automatically generate location info like country, state, city and even street names. Or if you know the location where a picture was taken, you can type it in and get the GPS location information automatically.