Google AdSense announced that the +1 button feature and personal recommendations will appear with display ads. We know about + button feature in google search, similarly it will appear on AdSense for Content and AdSense for Mobile Content display ad formats (animated gif,image, and Flash). So this is helpful for us to determine an ad’s relevance. It will help AdSense to deliver more useful ads to your users, which we think will result in higher returns over time.
For more information please visit the Inside AdSense blog.