The Ad Delivery Report shows you not only your traffic sources—whether that be Yahoo! or some of their partners—but also how your traffic from those sources converts. Combined with one of our analytics options, you can track measurements such as impressions, click-throughs, conversions and return on ad spend. You can also filter the results by account, domain, distribution channel and tactic.
http://www.ysmblog.com/blog/2009/09/10/do-you-know-where-your-ads-are/