Kill them all.
x86 has won. Really. Yeah, your port of linux to the PS3, or the ARM, or the toaster, or your dog is neat and all, but are you really going to spend the time and effort making sure it stays maintained?
This past weekend I tried getting X working on an ultrasparc 80. X.org has a wonderful bug where it can't handle how sparc's divide up PCI slots. it isn't rocket science: 0000 or 0001 as the prefix for the address. However this will be broken until (at least) X.org 7.3, which won't really be in any distros until, say, July at the earliest. If you look at the alpha releases of ubuntu, they haven't even bothered to release sparc at the same time as x86 and x64. there are a good number of sparcs out there. So I can only imagine what the story is like on rarer hardware platforms.
My proposal is to consider doing what microsoft did. Microsoft NT used to be available for MIPS, PPC, and X86. It was frustrating as you had to test and maintain all of them. Finally the axe was dropped and x86 became the only survivor (yes yes, later x64 and IA64 were added, but x64 is an extension of x86 and IA64 has intel jumping up and down on its chest to keep the heart beating.
Imagine all the effort and work being done on weird platforms that instead could be done on focusing on x86. You can't use the mac argument anymore as the macs are running on x86. If linux wants to be really dangerous, it needs to focus. Focus on a few key architectures. Go through freshmeat or sourceforge and kill the dying or abandoned projects. lean. mean. fearsome. consolidate your distros to 3 or 4 major ones and let the others inherit from those.