Lahey.

Power saving turns off nodes that have been sitting in PXEWAIT (and
are thus free) for more then a set amount of time (see sitevar
general/idlepower_idletime, which defaults to 3600 seconds).

The driver script is tbsetup/idlepower.in and needs to be added to
/etc/crontab at sites that want to do this. Even so, operation is
enabled by the sitevar general/idlepower_enable. Each time it runs, it
checks for nodes that need to be turned off, and then calls power.
Note: This should be a daemon not a cron job.

To be considered for power saving, you must add an attribute to the
node_type_attributes table called 'idlepower_enable', set to 1.

Locally, I hacked up stated and power to make the state transitions
legal so that stated does not whine. I added POWEROFF as a valid
transition from any state, to opmodes NORMAL, NORMALv1, and NORMALv2.
Barry's original patch already had a state transition for PXEKERNEL.
In power, I added code to look...