LinuxMCE is an add-on to Kubuntu that provides a complete whole-house media solution. It provides PVR and distributed media functions. It is stable, easy to use, and requires no knowledge of Linux and only basic computer skills. It allows you to set up a computer system that centralizes audio/video equipment, allowing you to access all media functions in other rooms with only thin clients. It supports home automation protocols including KNX, EIB, Z-Wave, DMX, EnOcean, and PLCBUS.
It is there already
A device to remotely power cycle a machine via IP network already exist. The german distributor allnet (http://www.allnet.de) sells such a thing.
You are able to remotely power on/off up to 8 devices from remote.