Disagreeing with Matt Cutts
blog.fairsoftware.net
blog.fairsoftware.net
The real discussion is that Microsoft is spying (legally) on their users behavior. And Google can't call them on it because they do the same, so they cry copy-wolf.
Didn't Matt categorically deny that Google uses Bing's users' clicks in Google's rankings.
edit: just after the 10:30 mark. http://bigthink.com/ideas/26740