Both Bing and Google are targeted towards mass market and I think people expect the same from both. If Google does it right, there is nothing more to invent. And even if there is, it is probably pretty expensive. It is so much easier to copy than to invent from scratch, just to get something almost exactly the same as Google :)
I am really interrested in what could Bing do to be REALLY different or better than Google. And if they did, Google would most likely do something very similar :)