For only the second time in NASA history, two astronauts made a spacewalk on Christmas Eve. Astronauts Rick Mastracchio and Michael Hopkins installed a new ammonia pump to fix the cooling loop on the ISS. You can't beat that Christmas Eve, even if you're Santa Claus.
NASA has their livestream going of the spacewalk and Spaceflight Now is covering it with play-by-play detail. After six hours, it seems the two astronauts have been able to fix the problem on the ISS. One astronaut said, "Houston, you've got yourself a new pump module."