As of right now Xbox.com is down. It is inaccessible. Outlook.com is also down. The reasonable assumption to make would be that the launch of the Xbox One and the update is placing considerable strain on Microsoft's resources, but the truth is we simply don't know why the site is down.
It appears to be a DNS issue and at this point we're not sure whether it will actually affect the performance of Xbox LIVE, or hinder people in their attempt to download the 500 MB patch the console requires to actually run on day one. From my own Twitter feed it appears as though people are currently downloading the patch without issue.
The Windows Azure Service Dashboard seems to suggest that only the North Central US storage service is experiencing partial service interruption, but that happened several hours ago. We have no real idea if that is the issue here, or if that's affecting Xbox.com.
We'll update when we hear more but, in the meantime, how are people going with the Xbox One? Have you been able to download the update — is Xbox LIVE currently working for you? Let us know in the comments below.
Update: Strangely, the Windows Azure Service Dashboard is down, but now xbox.com is up and running.