Bing was called out for copying Google search results in a revealing piece by Danny Sullivan, which chronicled a "sting operation" by Google to bust Bing doing so.

Not long after the article came out, Google’s Matt Cutts and Bing’s Harry Shum discussed the matter in front of an audience at a search event. While the two didn’t start throwing punches and kept things fairly civilized, the tension was not hard to spot. The two did take some shots at each other. Bing gave reporters the following canned response on the matter:

"We use multiple signals and approaches in ranking search results. The overarching goal is to do a better job determining the intent of the search so we can provide the most relevant answer to a given query.  Opt-in programs like the toolbar help us with clickstream data, one of many input signals we and other search engines use to help rank sites." 

Shum then posted a more elaborate version of that on Bing’s blog. Clearly, Google was not satisfied with Bing’s response however, and was not going to let that be the final word on the subject, as Google took to its own official blog, just in case not everyone saw Sullivan’s article. 

"As we see it, this experiment confirms our suspicion that Bing is using some combination of: Internet Explorer 8, which can send data to Microsoft via its Suggested Sites feature, the Bing Toolbar, which can send data via Microsoft’s Customer Experience Improvement Program, or possibly some other means to send data to Bing on what people search for on Google and the Google search results they click," wrote  Google Fellow Amit Singhal. "Those results from Google are then more likely to show up on Bing. Put another way, some Bing results increasingly look like an incomplete, stale version of Google results—a cheap imitation."

"At Google we strongly believe in innovation and are proud of our search quality," he added. "We’ve invested thousands of person-years into developing our search algorithms because we want our users to get the right answer every time they search, and that’s not easy. We look forward to competing with genuinely new search algorithms out there—algorithms built on core innovation, and not on recycled search results from a competitor. So to all the users out there looking for the most authentic, relevant search results, we encourage you to come directly to Google. And to those who have asked what we want out of all this, the answer is simple: we’d like for this practice to stop." (emphasis added)

I’m guessing this won’t be the last thing said about the issue from either company. Things are growing more and more bitter between these search rivals. Google has repeatedly downplayed Apple and Facebook competition, claiming that Bing is their main competitor.