Check out this site http://www.aishwaryaraisworld.com/ They placed thumbnails just over the ads to fake that you had to click on the ads to see the girl's picture or gallery... Is that acceptable ?
This ad placment is normal, many of sites are using these type of ad placements. I don see any TOS is broken.
yep, i too think the same. This is a small trick people use which is not a problem ever. many people use 728x90 ads with 4 image's which are more beneficial and give the adsense publisher a better CTR. This is just one trick of many which is allowed under adsense.