It has come to notice that Google has started placing ads on the Google Image search. Earlier banner or image ads were used, but now it seems that Google is moving towards a text ad format.
Michael Gray and other folks at Accuracast.com noticed that three text ads are now placed in the Google Image search. Earlier, only one banner or image ad was seen in the search results, which was either placed at the top or at the bottom.
It is guessed that Google is now testing three text ads in the Adsense format by placing them at the top of the image search results. According to some users, the two blogs listed above have screen captures and it seems that these can be trusted.