Yes, the cruise ships do lots of special things on Christmas Eve and Day. Most of the activities are kid/family oriented. I recently wrote such an article for USA TODAY.com; click on their travel section; then look for the columnists to click on; scroll down until you see my name; you'll see a few cruise articles listed including the one on holidays at sea. There is a section there on Carnival.
Luisa Frey Gaynor
Family Cruise Editor
when we went on the triumph on christmas 03 there was nothing special unless u were a young child. they had santa on the ship and they had a chirstmas mass for familys that go to church btu thast about all. they wernt even decorated for christmas and i forgot it was even christmas.