diberry - 5:16 pm on May 25, 2012 (gmt 0)
"Well first of all, I've yet to hear a reason WHY they would do it."
@netmeg, Timwilliams gave a why on the previous page (you probably cross-posted with it): "Now for the WHY. I know we are talking about the serps but this makes sense for both the serps and the ads. Google needs multiple advertisers for adwords to work in their benefit. If there was only 1 dominate advertiser in a niche that advertiser would not have to bid up their ad. Same goes for the serps, if a serp is dominating the sales then the advertisers go away. It's in google's best interest for everyone to make a little money and no one to dominate. Keep us all hungry but nourished..."
There IS an inherent conflict between Google selling adspace at the top of the SERPs and having control over who naturally lands on the top of the SERPs. As long as they're just letting the algo manage the SERPs through math without bias, everything's fine. But Yelp and others have alleged that they manipulate the SERPs to benefit Google, and that would be in violation of US law, which is why Eric Schmidt won a fun-filled visit to Congress last year.
What timwilliams describes would benefit Google. And it would be very hard to prove, so in terms of calculated risk, I would expect they might go for it - it would be so hard to prove to the Department of Justice's satisfaction, and no one else could force Google to stop it.