As a reminder and preparation for the upcoming "New Experience" this fall, Xbox Live will be offline for maintenance. Servers were shut down since this past midnight and it is expected to go live once again after 24 hours. Oh, and again, in case we were all still wondering, the Major reminds us:
When the service returns, you will not have any new features and you will not have the new Xbox experience update.
The New Experience is expected to land sometime this fall, although recent rumors have pointed to a November release.