In August, Google changed their policy for AdSense and will “allow multiple Google-certified ad networks to compete for display ad space on your site“. On adsense.blogspot.com it states that “This new capability will help you generate the most profit for every ad that appears on your site, whether the ads come from AdWords advertisers or Google-certified ad networks.” and:
We’ll slowly begin allowing ads from Google-certified ad networks to appear on AdSense pages over the coming months, so you won’t see an immediate impact on your ads or earnings. As new networks are certified, you’ll see them appear in your account. This feature will initially be available to publishers in North America and Europe, but we hope to roll it out to additional parts of the world in the future.
So this is good for all Google AdSense users. You can watch the promo video below.