Sadly, Fedora has dropped support for PowerPC hardware. I use Fedora on my Intel desktop and like it a lot, but was able to successfully install Debian 5.04 for PPC, the current stable version, on my G4 ibook with 512 megs of RAM using the first installation PPC CD and a cable internet connection. I just went with the defaults, and soon had a Gnome desktop and sound working right out of the box. The Debian installer is much easier to use than people make out, but it is a good idea to read the instructions carefully. The only tricky part was the wireless. See below.
To get the wireless working if that is an issue for you, you probably have the BCM4318 chipset and need some firmware.
After you have installed Debian and have everything working except for the wireless, become root and:
# lspci | grep Broadcom
This will tell you whether you have this quite common chipset. Then you need to check what kernel you are running:
# uname -a
Then, using the numbers, do something like
# apt-get install linux-headers-2.6.26-2-powerpc
# apt-get install build-essential
Once that's done, you need to tinker with the file /etc/apt/sources.list
This can either be done with an editor like emacs or, if I remember, there is a utility on the Gnome desktop. Either way, you need to add 'contrib' to the end of lines where the word 'mirror' occurs. Before you do this, the last terms will be something like "lenny main"
Once all that is done,
apt-get install b43-fwcutter
Your software should now be able to talk to the wireless card.
I should warn you that Adobe Flash does not support PPC hardware in Linux, so if you want Flash the best thing currently available is Gnash, which can play older Adlobe Flash media. If you are tired of apt-get, there is a GUI interface in Gnome to add software.