linux-headers-2.6.16 needs ppc_defconfig, in arch/powerpc/configs there are now a number of configs, for an Apple G4 system you can use pmac32_defconfig of course, but ppc64 has an issue of which to choose (already known). this bug has been added as a reminder to make sure ppc gets its defconfig at some point, as well as to help users wanting to test these headers for now :) solution for Apple G4 users: cp arch/powerpc/configs/pmac32_defconfig arch/powerpc/configs/ppc_defconfig this will get the headers in, but is a manual fix, and is probably not ideal...
Fixed in CVS, thanks.