Yahoo has just launched a new service much like adsense, it displays adverts relevent to the content on your site and you earn revenue from any clicks generated.
A lot of web company's are scrambling to keep up with Google I think. Hopefully they are thinking through all of their decisions and not just trying to grab the second place spot with all the same ideas.
Looks pretty close to the same thing as adsense yes.
80% of the traffic is seen through Ovt which is associated with Yahoo and not a bad move at all. I signed up months ago and just emailed them to allow me in the beta process.