But wait!
I bugged Jesse Keating about possibly spinning an updated boot.iso with the yaboot from F11-updates. To which he replied, "That's just a pungi compose with updates enabled. Can't you do that?" And behold, he was right. So I did that. And then I had a couple of awesome people test it. And it worked.
You can find the updated boot.iso here:
http://jwboyer.fedorapeople.org/boot.is
There is no warranty, it is not guaranteed to work, and if it makes your system catch on fire it is not my fault. But hopefully people find it useful and we get a massive explosion of ppc64 systems installed with F11 because of it.
Moral of today's story: Ask not what Fedora can do for you, but how you can use Fedora to scratch your own itch!