I think you can make the argument that in order to have a "free market" of ideas (when it comes to building the best search engine) you shouldn't cannibalize th

I think you can make the argument that in order to have a "free market" of ideas (when it comes to building the best search engine) you shouldn't cannibalize the ideas of your competitor. If Bing's signal consisted of some generic method for mining clickstream data that just happened to pick up on clicks originating from Google, then this wouldn't be a problem. The fact that they're deliberately deconstructing Google URLs (per the Microsoft research paper that Matt cites) makes this questionable.