It is a cool news for Google AdSense publishers.
From October this year the Google AdSense display ads will be carrying a +1 button, thus enabling a visitor to endorse an ad and make it more likely to get displayed on his social connection, just by a click.
Google feels that this will make more readers to take notice of the ads on the site of a publisher. This will in in turn lead to more clicks, eventually resulting in higher returns.
For example, after coming across an ad on software application a visitor named 'X' might feel that his friends will benefit from the ad, and so he +1's the same. Later when his friends and other contacts sign in to their Google accounts, they find that it has been recommended by X. recommendation by a known person will certainly enthuse them to visit the ad themselves. So ultimately this way the ad is likely to get more clicks, finally resulting in more ad revenues for the publisher.
It may be noted here that there will be no revenue for +1 button click, as it itself will not be counted as a click on the ad.
+1 will appear on AdSense for content (including mobile content display ad formats, such as Flash ads, animated gif and images). In case a publisher does not wish ads published on his site to be carrying +1 button, then he has the option to opt out by signing into his AdSense account. In fact that option is already open to him. It is not that he has to wait till October.