Seeing as there are people who want work on Max OS X (ppc) support and to speed up their work, so they won't redundantly search for stuff which needs to get implemented and so they can spend time on implementing it further.
There was some work done already during GSOC 2011, which didn't get applied (due to not being finished? / missing signed-offs).
Anyway some time ago I tried to apply those patches and got Mac OS X to start booting, you can see description and some screenshots at this address: http://www.emaculation.com/forum/viewtopic.php?f=1&t=7047
Links to those patches with my comments here: I tried them with latest tree, mixing some current stuff from mailing list (mainly trying some filesystem things).
http://lists.openbios.org/pipermail/openbios/2011-August/006653.html dummy get-key-map
http://lists.openbios.org/pipermail/openbios/2011-August/006615.html http://lists.openbios.org/pipermail/openbios/2011-August/006616.html http://lists.openbios.org/pipermail/openbios/2011-August/006618.html file-system / partitioning stuff - may need some changes due to recent patches
http://lists.openbios.org/pipermail/openbios/2011-August/006617.html after "Call kernel!" it stops drawing to screen
http://lists.openbios.org/pipermail/openbios/2011-August/006619.html local forth variables, I tested new implementation (from few days ago) and it also works
http://lists.openbios.org/pipermail/openbios/2011-August/006620.html I think I stumbled upon it not booting without this one, but currently can't reproduce
http://lists.openbios.org/pipermail/openbios/2011-August/006651.html 0 > boot cd:\:tbxi >> openbios panic: Unexpected exception fff26500
http://lists.openbios.org/pipermail/openbios/2011-August/006623.html for drawing apple logo (from my tests it seems badly positioned but it may just want some other -g option to qemu)
https://lists.nongnu.org/archive/html/qemu-devel/2011-08/msg01418.html I can confirm that it stops after "COLOR video console at 0x80000000 (800x600x32) without this
I will certainly test any new patches that appear ;)
Amadeusz