Mainly a note for myself, in case I need it again in the future.
And the original blog post is here.
This will turn on a Mac Mini (at least PowerPC arch, not sure about Intel), running Linux, the moment it has power again.
echo 'server_mode=1' > /proc/pmu/options
Edit & Note: This option seems to be reset after every boot to. So add it to
rc.local or something.