I think a switcher such as westy describes would have to operate similar to the Radio Shack switch box that I got for my mother-in-law a few years back: you can teach it IR commands from other devices so that (for example) the DVD power command switches it to input 2. That's the only manageable way to do what westy describes, and in that scenario it isn't much more complex than the existing IR-controlled HDMI/DVI switchers.