Google Adsense and the +1 button
Previously, they launched the +1 button on Google search for publisher sites to make it easier for people to share and discover content across the web. Soon, users will be able to also endorse specific ads and make those ads more likely to appear on their social connections. Google believes these recommendations will help readers notice ads on your site more, which could lead to higher returns over time.
“For example, take Susan, who sees an ad for a good deal on flights. She +1’s the ad, thinking her friends might value this deal. Now, when Susan’s friends and contacts are signed in to their Google accounts, they’ll be able to see Susan’s picture across the bottom of the ad, with a note saying she +1’d it.” quoted from Google Blog Post.
Display ads will be much more powerful when people see their connections have chosen to endorse them, which will lead to a better advertising experience and higher returns for advertisers and publishers.
If you prefer not to show the +1 button on your display ads pages, you can opt out anytime by logging into your AdSense account.