It was operating FCO-ATL and diverted to SNN due to smoke in the cabin. Was supposed to then fly SNN-ATL, but was diverted to CVG because of weather at ATL last night. I'm guessing it's still in CVG, as there's no evidence that the a/c continued to ATL (as a revenue flight or a ferry flight), nor was if ferried to DTW or MSP. I'm guessing the crew ran out of duty time and DL put the passengers on flights to ATL (There was a DL charter flight between CVG and ATL early this morning, so maybe this was to get passengers on this NW/DL flight back to ATL.).