I thought FC4 was pretty bad at setting up WiFi,
but FC5 seems even worse.
Basically, I was only able to do it "by hand",
writing out /etc/sysconfig/network-scripts/ifcfg-eth0
and giving explicit route/ip commands to start WiFi working.
I gathered from the documentation that FC5 relies on NetworkManager,
but this did not appear to be running after installation.
In my case, when I chkconfig-ed NetworkManager on, and re-booted,
I was not connected to my dhcp LAN,
and no NM applet appeared in my KDE panel as I had expected.
The whole WiFi setup is a bit of a mess, in my experience.