Yahoo! Publisher Network Added Advertising in RSS feeds
We're pleased to announce another method for you to maximize your revenue and bring value to your content properties: Advertising in RSS feeds is now available through the Yahoo! Publisher Network.
This new product feature allows you to place Yahoo! Search Marketing ads within your RSS feeds. The ads that appear may be relevant to a specific article or post, or to your content in general.
For more information on Ads in RSS or to activate ads in your feeds, please visit https://publisher.yahoo.com/portal/AboutRSS.php (requires account log-in)"
It seems like YPN has started allowing ads in RSS feed. Will try it out.