In the past, Facebook used to work with a third party ad network, but this time Facebook is acting like the ad network and is working with both the advertisers and the publishers. If Facebook controls the process from soup to nuts, it means more money for them. The beauty of the plan is that if it works, Facebook makes money, the developers make money and everyone is happy.
Facebook says that it is no longer looking for partners, but is taking names just in case there is an opening down the road. If interested,click on the sourcelink.
source: Facebook via Android Central