This morning TechCrunch is reporting that Microsoft's Outlook.com and Hotmail email services have been down since 4:00PM EDT yesterday. That puts the services past 12 hours or so since they were last accessible.
SkyDrive and Calendar were also affected, but it appears that those services have been restored. Early speculation tied the outage to the Hotmail to Outlook.com migration, but an official statement from Microsoft denied that the migration had anything to do with the outage.
As of this posting I am unable to reach outlook.com and attempts to login to an old Hotmail account also failed. TechCrunch is reporting that the outage is not a total systems blackout though with some users still being able to reach the service.