I have always suspected that the real value of Bing for Microsoft is to prevent Google's data mining of queries originating in Redmond.
If I'm in the business of giving horse racing tips and I read your tips to see what your strike rate is compared to mine, that's one thing. If I start tipping the same horses as you, purely because you tipped them, that's quite another thing.
edit to expand: If the measure by which a search engine evaluated itself was advertising revenues, they'd all have massive intrusive adverts, and no users. The only viable measure can be the quality of the search results themselves. As a happy coincidence, if you build something capable of delivering high quality results, you can very easily use that to produce highly relevant adverts. Imagine that each advert is like a little webpage, and rank them just the same as you do for normal webpages. (caveat: there's no link graph for adverts, so we're reduced to using a simpler text mining approach, eg bag of words vector space la-di-da).
This whole episode points to the sort of counter-espionage operations the two companies are engaged in. Look how important a propaganda victory is for Google? It strains credulity to believe that the release of this information on the day of the panel discussion is pure coincidence.
MS are desperate to regain control. Google will soon launch their own web-centric OS properly, and bam, MS will have no business apart from selling to an ever-dwindling number of companies who can't believe MS don't rule the roost any more. In 20 years they will simply cease to exist if they can't come up with a world-beating online product and win back control of people's computing lives.
Notice how they're diversifying into games and search in order to prepare for the worst case; that their core OS and 'boxed software' business fails.