AdSense has launched a new beta test called Vertical Images, where an image would take the place of an ad within an AdSense ad unit. These images – which are generic, and not company-specific – act similar to an ad link unit, linking to a page related to the ads and image that appeared in the ad unit.
Here is an example of the new vertical images ad unit:
Publishers are allowed to click the images themselves (just be careful not to accidentily click the ad below it!) but you cannot click on any of the ads that appear on the results page, just as how publishers can click on ad links keywords but not on any of the results.
And good news for international publishers, this beta test is international, unlike many of the beta tests which are US-only. The vertical images appear in skyscrapers (both the regular and wide skyscraper, and all of the ones I have seen so far have taken the top spot in the ad unit. There are also reports that these vertical images are displaying in ad units that are specified as text only, so you do not need to enable images in order to see them.
This is an interesting experiment, since many publishers found success by putting images very similar in size to these next to or above ads, finding it draws the eye to the ads. However, there are rules publishers must follow in order to use this technique. But with AdSense now trying a very similar technique, they can easily track CTR rates and see how the clicks on the images compare to clicks on the first text ad, as well as those who may click the image, then hit back and click on that first text ad.
This will be one to watch, especially if it becomes widely released (it is only on a limited number of page views currently) or if it morphs into its own ad unit or option where a publisher could chose to display vertical images if they wish.