Windows Azure, Microsoft’s cloud platform for building and hosting web applications, suffered an outage yesterday that brought down several websites that rely on the service. The outage began sometime Tuesday, and ran until just before 3 am (Pacific time) yesterday. The outage impaced Azure users around the world, including the government of the United Kingdom.

The cause of the problem was apparently quite simple: yesterday was Leap Day. It seems Azure began having trouble when the calendar began kicking over to February 29th. In a blog post addressing the issue Bill Laing, Microsoft’s Corprate VP for Server and Cloud and the head of the engineering team responsible for Azure, said that the problem had been found and fixed. He said that the situation was resolved for most users, but that “some sub-regions and customers” might still be having trouble connecting to the service.

Laing also promised that more information, including a fuller explanation of what went wrong, would be available soon. He also said, though, that the team’s main priority at the moment was getting service back for all users.

Are you a Windows Azure user? Did you lose service yesterday? Do you have it back yet? Let us know in the comments.