TVs have had this feature for years. HDMI CEC will let you sync up your devices and cut them on together. its been on the Playstation 3 for i while. i used to use it before i got a Harmony remote. i guess it is new for Xbox fans because the 360 never supported that.
I had this harmony remote for my xbox now unless you mean something different
http://m.cnet.com/reviews/logitech-harmony-advanced-universal-remote-for-xbox-360/31599239