The rumors have been building for a week now, here is the first thread i have found on the topic, started by Brett Tabke at WebmasterWorld, under the featured title name Yahoo Contextual Advertising Program. Silicon Valley Watcher came out with the most recent story, they always start a big buzz on things. The first rumors on this came from Waxy.org, where they think that the Yahoo! ads look like what is found at this blog.
All I have to say at this point is http://publisher.yahoo.com/. More to come...
