I got XFree86 4.0 building on my Yosemite G3 over the course of this weekend, but I ran into a problem where it will not recognize my Rage128 as one it has acceleration for, since mine is a Rage128 RE, according to its startup stuff. I've got a RevB Yosemite G3, with a PPC750 at 400MHz in it. Xpmac works, and I haven't tested the prereleases of XF68_FBDev, as the ones out there have expired by now. (The ones with Rage128 support.) However, Xpmac is giving me a couple problems. (Crashes with Enlightenment, doesn't like transluscent windows.) as well as some other stuff. As far as XFree86 4.0 goes, I had to leave out Int10 and vgahw support, to make it work. Both needed libx86emu, which breaks with "Relocation truncated to R_PPC_REL24 BLEH" for each function, then undefined references for the same functions.
-Adrianne