Apple has this. It's called Boujour sleep proxy, and it allows a always-on device like a Airport or AppleTV to claim the IP address of a sleeping Mac, waking i

Apple has this. It's called Boujour sleep proxy, and it allows a always-on device like a Airport or AppleTV to claim the IP address of a sleeping Mac, waking it with a WoL packet when traffic for that device comes in. It's probably pretty useful, but is annoying on a managed network, as it spams my arpwatch system every time the IP is transferred between devices.