After an industry wide outing of Ask playing the Google Adsense arbitrage game, until today these practices have not stopped! You will still be able to find Ask search ads on Google network, that lead to Ask SERP's full with paid search ads of... Google!
Today I saw a Yahoo Ad popping up in the Google Network. The AD was saying:
Looking for Doodle? Find exactly what you want today.
See picture below:
So does this mean that Yahoo has started to play the same Google Adsense arbitrage game as Ask has been playing for the last couple of months, with the only difference; the Yahoo advertiser is paying a multiple of what Yahoo has paid to get the traffic to the advertisers Ad!