pocster,
LinuxMCE automates the turning on and off of a device. Unfortunately, it does do so only directly to the device, i.e. you can't atm say, please use this device device to turn on/off that device. Apart from that, in my house, LinuxMCE automatically dims the lights, turns my display device on, my amp on, whenever I select the TV scenario, or when I select a video to play. When I select music to play, it does not turn on the display device, but the amp only. Who needs a display for listening to music. When I end TV (or video or music), the lights turn back on, and after 15 minutes of slide show, it turns off the display device and the amp. I did not configure any of this, it is all done automagic, after telling LinuxMCE about my setup.