If you are a Yahoo Ads publisher, beware about having images beside your yahoo ads. Google doesn't have any problems with it but yahoo is more strict on this issue. At digitalpoint, yahoosarah replied to a discussion about this topic and I quote.

All,

After reading the discussion on this thread, I wanted to clear up the issues around images and Yahoo ads.

Bottom line: Images next to ads are not allowed in YPN unless there is a clear distinction between the images and ads.

Specifically from our guidelines:
• The user must be able to tell the difference between the Ad Unit and other content on the publisher's page.
• The Ad Unit cannot be obscured in any way
• The Ad Unit must be clearly labeled as "Ads by Yahoo!" and this label should not be confused with other advertising or links on the publisher's page.
• Images or other media cannot be associated with the Ad Unit.
• The Ad Page must not actively encourage users to click on Ad Units.

Hope this clears up the confusion. Feel free to send me an email if you have questions. Thanks
YahooSarah

In the thread, one person actually asked yahoo to check out his site for compliance. The site it http://www.allfreeflashgames.com/. If you notice at the center, there's a clear border separating the ads and the images.

So do an inventory check of your sites and find out if they're are compliant.