Google is making a fairly significant change to how AdSense works for advertisers.

In short, Google is dealing with what is known as the “blind network problem” – advertisers pour money into AdSense, and they get a sense of how the campaign performed in aggregate, but they have no idea which sites did great, and which sites did poorly, or often, even which sites they ended up on (unless they specified via the relatively new site specific buys on AdSense.) This new set of reporting addresses this issue, allowing advertisers to determine where their campaigns are doing best, and then they can optimize accordingly.

This is significant for publishers, too. If you care at all about how much money you make from AdSense, you will want to figure out how to ensure your site is one of the better performing sites.

I also think it will help knock down some of the made-for-AdSense sites … assuming they’re not among the better performing sites, and/or advertisers have more control to ensure their ads don’t appear on smarmy-appearing sites.