Celebrity's Millennium remains at the Fincantieri shipyard at Palermo, and the repair process to its damaged propeller is continuing. As of this afternoon, Celebrity told CND, "The repairs and system checks are going well, and the vessel is expected to sail and be on time for its next scheduled cruise from Barcelona July 24."
Update/clarification July 18: Celebrity clarified for CND that the damaged propeller blade (which couldn't be removed in Civitavecchia causing the cancellation of the two cruises) was removed and the new blade was installed promptly in Palermo. The testing that was going on is testing on the completely repaired propellers.
Since the ship has nowhere to go (it doesn't have to be in Barcelona until July 24), other minor maintenance is being performed until it is time to leave for Barcelona.