ftp://zeniv.uk.linux.org/pub/people/dwmw2/fc4-pegasos-20060304
More usefully, use whatever you have locally as seed and fetch it from rsync://zeniv.uk.linux.org/ftp/pub/people/dwmw2/fc4-pegasos-20060304
It should hopefully manage to install on the new dual-core G5 machines, and it also has a rebuilt Thunderbird package, which we've been waiting for for a number of months. This still isn't an _official_ update but it does the job.
I'd very much like to hear from you if you tried it on a dual-core G5. Especially if it worked.