iPhoto '09 has a Places feature that let's you search and organize your photos by location. It does this my examining the location information a GPS-enabled digital camera or iPhone embeds into every photo snapped.
If you've been taking digital pictures for a long time, or you don't have a GPS-enabled camera, you have lots of photos that don't have location information. No worries - iPhoto '09 gives you a way to add location information to your photos.
In iPhoto, select a photo, Event or group of photos shot at the same location. Then, click the Information button (the little white circle with an "I" in it in the lower-right corner of the photo or Event). The photos or Event will flip over (like a card) to show you more information.
Set Location for Photos
Click on "event place" (if you had selected an Event) or "place of photos" (if you had selected a group of photos). Next, type the name of the place the photos were taken. As you type, iPhoto will list locations. If you see the location you want, scroll down and click it. If you don't see the location, click "Find on map" to use a map to select the location. Once you've chosen the location, it will be applied to all the photos in the Event or group.
Using iPhoto Places
Now, you can click the Places library to bring up a map. Each red pin marks a place where your photos were taken. View your photos by location by clicking the red pins.
Zoom the map to see more pins - more locations, even cities and popular landmarks (like the Golden Gate Bridge and Empire State Building).