We announced Bing Visual Search today. It’s one of those things that’s easier to see than explain – check it out at www.bing.com/visualsearch
Steve, if your bing locale is set to UK then the visualsearch URL returns a "lets try that again" (404). To get to see visualsearch you need to change your Bing locale to US (as with a few other Bing things it's US only at the moment)