About wireless controllers..... even the best one's ont he market still totally suck. I got a wavebird for christmas (nintendo brand controller) and even though it's arguably the best on the market for any platform, it still cuts out from time to time. Every time my neighboors use their cb station it goes crazy. The Microwave also seems to cause minimal lag.
Also keep in mind that the reason the nintendo controller is so much better is because nintendo games use far less buttons. Think about it, the way the controller and gamecube games are designed you can really only hit a maxium of a direction and 3 buttons at once. I think that has a lot to do with how good the response time is.
So to sum it up, everyone thinks it's the best and it's really not so hot, so I can only imagine what kind of problems you'd have with a totally wireless cabinet. Remember you need enough frequencies to carry the audio, the video and all of your controls. (a wireless kb would NOT work, you'd have to hack gamepads.) That seems like a pretty tall order to me.