ap_Rhys - 10:25 am on Sep 3, 2012 (gmt 0)
I for one would be out of business if Google served ads that were 100% relevant to some of my sites. I get ads that are relevant to my *audience* not my site, and that has worked out pretty well for me (specially this year).
Which is one reason why some people with general, wide-ranging or untargeted sites are doing well and others with expert content sites are doing badly.
Makes no financial difference to Google where their ads appear but probably gives Google better relationships with large organizations - the ones with commercial clout.