Update: Xbox Live's earlier sign-in issues appear to be resolved. A separate problem pertaining to Diablo III, however, continues to persist.
I was just able to sign into Xbox Live on my Xbox 360 without issue.
Xbox Live is currently experiencing sign-in issues and those claiming responsibility for the earlier PSN attacks, and the bomb threat against a flight carrying Sony online president John Smedley are taking credit.
Is anyone having issues with the Xbox Live Login servers?
— Lizard Squad (@LizardSquad) August 24, 2014
The good news is, Microsoft is fully aware of the issue, and has this message posted on the Xbox Live status page:
Xbox members, are you having a hard time signing into Live? We’re aware of the issue and working hard to find a solution as quickly as possible. Thanks for being patient in the meantime. Please check back in a half hour for an update on our progress.
The issue does not appear to be entirely widespread. While I did have issues signing into Xbox Live with my Xbox 360, my Xbox One did not pose any problems.
We've reached out to Microsoft for details on Xbox Live's current issues and will update this story if more information emerges.
The most confusing things about these attacks is I still did not know the ultimate goal. They have certainly crossed a line of annoyance and into a dangerous security issue, so I am glad the authorities are working on the case.