There have been similar types of devices in the past yes, not sure what all has been available this console generation though. I have seen some people try using some very convoluted adapters in order to use ps3 controllers on 360s, but those are all kinds of stupid... because of the way MS checks controllers, and how picky they are about what they do and do not allow, you have to physically have a 360 controller attached (to get past the controller authentication MS has) to the cord as well as the ps3 controller. 

If this thing somehow manages to have &lt;1f of lag, I'm in. Not getting my hopes up for that though. Still, neat idea.