A monopoly controls only the supply side of a transaction, so it can’t change whatever it wants.

I agree with Michael Arrington about his post. Google is monopolising ad deals in its own because of the demand and supply. If Google were to increase the prices, buyers will just stop buying. And the sales will just go down. Advertisers will only buy for what they want to get from the ads.

I believe that Google-Yahoo ad deal is going to be beneficial for all advertisers as the inventory expands into a larger market.