Microsoft is having problems with their login services, for both Xbox Live and Microsoft account services (for what it's worth, logging in to Office 365 apparently works), and lots of users are looking for information on the outage, which is approaching an hour now.
On the Xbox Live Status page, Microsoft has conveniently offered a notification system to be alerted when there are changes to the status:
Yeah, so that's a problem. In order to be notified that the Microsoft account services, which are down across the world, are back up, you have to log in to those same login services.
So much for that idea. We'll keep you posted on the service outage as it unfolds.