Both Xbox Live and PlayStation Network, the online services for Microsoft's and Sony's game consoles, have been intermittently down on Christmas Eve and Christmas Day, according to tweets and status sites.
A hacking group called Lizard Squad has taken credit via Twitter for a DDoS (distributed denial-of-service) attack. The group's involvement is unconfirmed. However, according to Business Insider, Lizard Squad had been promising to play Grinch since the start of December.
The Xbox Live status page currently shows Xbox Live Core Services as "limited."
The PlayStation Network status page shows the service as currently being offline. Three tweets from @AskPlayStation over the past 20 hours, including one three hours ago, have all noted "issues accessing PSN."
Downdetector.com, which tracks outages, has been following both services' problems. It shows that PlayStation Network has been on a rollercoaster ride since about 5 p.m. PT Wednesday. Downdetector.com also shows that Xbox Live has had problems off and on since about 3 p.m. PT Wednesday, though not nearly as many as the PlayStation Network.
Update, 11:35 a.m. PT: PlayStation Network's status page now shows the service as offline.