A Form of Google Paid Inclusion?
One of the reasons Yahoo Search is somewhat less trusted in the industry is because they have a paid inclusion system. In order to increase rankings to your site, all you really had to have was enough money. Very simple for people to buy rankings of some form or another. (This is all moot, of course, when Bing takes over their search).
Google is always said to have shied away from this, because it hurts the integrity of the results. Instinctively, this seems like a good thing to us. Even though there are round-about ways to "buy" rankings with cleverly placed paid links, at least Google wasn't endorsing it, and could stay on the high road.
But is Google really have a form of paid inclusion, hidden deep within one of it's services? Perhaps.
I have heard it on good authority from an Adobe insider that using the paid version of Google Site Search has actually improved their rankings. This might be correlation, of course, because any tweaks Adobe made to their site to improve the the accuracy of Google Site Search would surely help the regular Google bots as well.
And Adobe's situation would probably not apply to everyone, as they are obviously a large partner with thousands of pages that already had high authority. But it's interesting to think about. Someone with enough resources at their disposal could test this theory pretty easily.