Diablo 3 servers and web services are scheduled for maintenance downtime on Tuesday, July 3rd. Quoting from the Battle.net forums:
We will be performing scheduled maintenance on Tuesday, July 3rd. Maintenance will begin at 5:00 AM PDT and conclude at approximately 11:00 AM PDT. During this time, servers and many web services will be unavailable. Thank you for your patience.
Source: Battle.net Forum