Back in 2007, Google had announced that they were missing out on as much as $200 million per year because they were not monetising their Image Search product. After that, there was no report of anything being done about this till some users spotted a single Sponsored Links result among the images, as reported on TechCrunch.
Today, though, a full line of three Sponsored Links are showing for most searches carried about by a handful of user accounts that have been selected to participate in the test.
The paid search listings that appear on Image Search results are not the same as those on the Web Search results page. The reason behind the difference in ads delivered is not yet clear. The ad copy of the ads that are common to both is the exact same, which makes one think that Google has some other selection criteria for delivery of these ads.
The presentation of the Sponsored Links above the organic search results here is different from that on the Web Search pages. The 4-line ad format with 3 ads placed side-by-side in the images results looks better than the 2-line format with 3 ads placed one below the other on regular search results as the organic image results are also shown side-by-side rather than one after another.
Why Google hasn’t done this earlier is a question worth asking.