Yahoo's Flickr has apparently begun testing a new contextual ad format from the recently launched Yahoo Publisher Network, according to a post on Peter Forret's blog (link thanks to Olivier Travers); Forret terms the ads "image-enhanced topical link units" that seem to be a hybrid of Google AdSense "link units" - a collection of one-line topic links that lead to ads on that topic - and Yahoo Publisher ads. The images grab attention, and the topic links filter customers by interest and direct them to more relevant ads.