During the last week of August, the AdSense referrals feature will be retired for both AdWords advertiser products and Google products. After careful consideration, they believe that they can best serve their advertisers and publishers through two alternative offerings, AdSense for content and DoubleClick Performics Affiliate.
Beginning in late August, any remaining referral ads on your blog will no longer work, and will appear as blank space on your blog. In order to prevent a decrease in your AdSense earnings, they strongly encourage you to replace all referral ad code on your blogs with AdSense for content ad code prior to the last week of August. You can get this ad code by signing in to your AdSense account, selecting the AdSense Setup tab, and choosing AdSense for content as the product.
If you'd prefer to manually select the ads that appear on your blog in the future, they encourage you to check out DoubleClick Performics Affiliate.