I don't know if I'm in the twilight zone too, but i have had a million different powerbooks and ibooks. They all had a wpa option on them and worked perfectly on my newer wifi. Even ubuntu on powerpc had wpa. I do believe powerbook titanium series and before did not include an airport extreme card it just had an airport card that only offers wep. You can set newer routers to wep temporarily to do updates as I have done.
I have just run into a powerbook with osx 10.4 that only gives the wep option on an airport extreme card that has been tested to have a wpa option. I think the retail version of osx 10.4 has this update in it and this osx i have on this powerbook must be an update from osx jaguar without the wpa update.
Just to be firm powerbook/ibook/imacg5/powermac all use wpa as an option with the right mac osx software. I have never used osx 10.4/10.5 on pentium macs only snow leopard and that had wpa. You may have to plugin manually to the network and update osx to gain the feature. I'll come back and post if I get it figured out.