Someone actually built a Bing-based instant search a while back: http://www.istartedsomething.com/livesearch/ http://www.istartedsomething.com/livesearch/ It's

Someone actually built a Bing-based instant search a while back: http://www.istartedsomething.com/livesearch/ http://www.istartedsomething.com/livesearch/ It's not nearly as responsive, dunno to what extent that's imposed by MSFT's server infrastructure though.