Update: Xbox Live has returned to normal operations (this update 23:15 GMT). No official word on the cause, although a number of hacking groups have claimed responsibility, the timings of the claims are somewhat suspect. More information as we have it.
The original story is below, posted at 20:37 today.
Xbox Live is currently down for the second time this week. Here is a report from Xbox.com
This is all we have to tell you at the moment, We hope it’s back online soon. If you’re having Issues leave us a reply.
Hackers called Phantom Squad are trying to claim that they had done it.
We are going to shut down Xbox live and PSN this year on christmas. And we are going to keep them down for one week straight #DramaAlert
— Phantom Squad (@PhantomSqaud) December 9, 2015