Images Near YPN Ads Definitely Against Yahoo! Terms
There has always been a lot of discussion and not a lot of clarity regarding Images near adsense, Even the Google terms are unclear and emails to Google asking for clarification didn't help. It seems Google allow, or disallow, images near adsense on a site-by-site basis.
With the Yahoo! YPN network, However, There is no confusion. It seems from the outset Yahoo have made it perfectly clear that images are not allowed near adverts. Some webmasters applied the same tactic they apply to adsense by placing pretty images near their YPN adverts, And most soon received this clear, Concise, Frank warning from Yahoo.
You are in violation of our obscuring guideline. A user must be able to tell the difference between the Ad Unit and other content on your page. The Ad Unit should be separated from other page content, including images, by a border, a clear difference in color, or some other means. Images may not be used to draw attention to the Ad Unit or as a click incentive. I hope this information helps you to understand the requirements more clearly. Please let us know if you have further questions.
If only Google could be this clear regarding images near adsense.
If you do use images near adsense, Or YPN, I wouldn't worry too much. It seems the consensus is that Yahoo and Adsense send "warnings" to publishers telling that their image placement is in violation of the ToS instead of outright banning them.