I have just run another tcpdump on a clear cache, and I cannot see any connection to CNN, so if I had to bet and the bet was small, I would bet on a proxy and store being used to deliver the content.
Which is odd though because there is no need, the big sites will pick up on this soon enough if they are doing it, I suppose framing the content does alert sites to this being done, but it is not as detrimental as creating a scenario of duplicate content, and you will alert them anyhow if you climb high enough on the content.
I imagine they will just ensure it does just frame, and allow for the frame to be removed by the browser and in their interface strip, that tends to keep people happy, but if they grow they will run into the similar problems google has, where the content people will want a slice of the action.