Xbox Live is apparently on its knees before the malicious activity of a group of DDOS fans, although from here it seems to be working perfectly.
About an hour ago, a hacker group tweeted out that Xbox Live was down - the usual means for taking responsibility for a DDOS attack or other malicious activity.
The group, whose antics bore us, threatened to repeat their action over the holidays.
It's not clear how much impact the alleged action had. Polygon reports some users are reporting experiencing error messages, but didn't link to examples. GameInformer reports a number of social functions went down, at least temporarily.
Update: here's a bunch of Redditors reporting the problem, so it looks like it might be contained to North America, and possibly intermittent. That would explain why other users have not encountered problems.
At time of writing, the Xbox Live Status page doesn't show any problems, and Microsoft is normally remarkably good at notifying users of issues. It has updated the page during DDOS attacks in the past, for example, although it doesn't usually explain the reason for downtime.
It's possible that whatever impact the group had has already been nixed. Microsoft has not commented on the temporary down time.