Alfresco is a very open platform for building document management and web content management solutions. We have a number of customers that use ad networks.
However, out of the box we don't support any specific ad network integration - this is usually done by whoever is putting together the final solution.
So the answer to your question - yes, you can integrate Alfresco with Openads, but we don't support any specific ad management solution. We manage the content that gets displayed along with the ads.