I think we're missing the bigger picture.
Google started with nothing and said, how can we make sense of the Web as Observers - they invented "Linking".
Microsoft started with the #1 Browser (or whatever) and said how can /we/ make sense of the web, and they said "clicking and sticking".
This is information Google didn't have, but they built a browser to get it because they understood Microsoft's advantage.
To leverage its browser advantage, MS needs a syntax which connects a term searched to results pages. It would naturally code all the available search engines as the natural source of this relationship. It is less interested in the list of results, than it is in the clicked-through link; and MS would argue there's a difference, while GOOG would argue that it picks the candidates, thus MS is leaching.
In response, GOOG will likely engage in very heavy duty "testing" of this theory by designing proxy servers which reports consistently misleading results for more and more search terms.