Clark - 8:36 pm on Oct 31, 2010 (gmt 0)
Quite some time ago, Google introduce a tool to (ostensibly) help you determine conversion.
Clearly they've been interested to know every single aspect of conversion for ages. However, they used it for far more than many might have anticipated.
And now they have absolute control of how they want to shape traffic. And clearly they will tune the knobs until they profit the most out of it.