I have a Mac Mini with a 1.5 GHz PowerPC G4 processor running Mac OS X Leopard 10.5.8, which is the last compatible OS for this processor. Installed (and working) is iPhoto '09 with the latest update being version 8.1.2 (424). You can download the update for this version from Apple here:
http://support.apple.com/downloads/DL970/en_US/iPhoto_812.dmg
Try this if you want to retrieve the photos:
First, back up any and all iPhoto Libraries existing on the old machine to a safe place, like the Desktop (using Finder, drag /Users/FIL/Pictures/iPhoto Library to Desktop).
Next, run the install package from the downloaded update file if you can, installing it in the same location as the current iPhoto program. You may need administrator privileges, and if it asks if you want to install over a newer version, say 'yes'.
If it installs successfully, run and check the version under the "About iPhoto" menu item, but DO NOT UPDATE! I did this because it said iLife '11 was available and it broke my install, so I had to dust of my old iLife '09 disk and reinstall from scratch.
Now quit iPhoto, then re-open it while holding down the option key. This will give you the option to open other iPhoto libraries. Select the previous library (select "Other Library..." button if what you want is not in the view window, then navigate to Desktop/iPhoto Library) and click "Choose". You should now see your FIL's pictures.
If the install didn't work, you can try copying the iPhoto Library to a disk or flash drive and opening them on a different Mac with iPhoto + the option key as described.
The caveman approach would be to navigate to the desired iPhoto Library, then right-click (or ctrl+click with Apple Mouse) on it, select "Show Package Contents" menu item, then salvage all *.JPG files from the Originals, Modified, and any other folders.
Good luck with your task, and my best to your FIL in his new residence!
