About four years back I wrote a post on waking up machines in Backuppc.
This was a simple and fantastic way to wake up each machine to back it up. For a while I was actually waking up the backup server from the router and it would then backup the machine. At a set time the backup server would then shut down.
This was going to plan until I upgraded to Ubuntu 12.04. The backup machine was unable to boot up without human intervention and backuppc had an issue requiring the downgrade on the samba component. Most would expect the latest version of a OS to be better than the previous. Sadly this is not the case with Ubuntu.
Well now in this post on Good Job Sucking the author describes a way to wake the machines, discover if they were up shut down and if so turn them off. It a great idea. Only one caveat I would say is that most Windows machines would be set to sleep after a period, so this technique may not be needed for desktop machines.
Well worth looking into I think.