updated 03:37 pm EDT, Thu August 21, 2014
Affected services included Photos, Keychain, Find My iPhone
Many Apple online services -- and "some" percentage of users -- were caught in a brief but severe outage on Thursday, according to the company's official system status page. This included every iCloud service, such as Photos, device backups, Keychain, Mail, Documents in the Cloud, and web apps. Also impacted were Back to My Mac, Find My Friends, Find My iPhone, and iMovie Theater.
The trouble appears to have begun shortly before 2PM Eastern time, and resolved shortly after 3:30PM. During the downtime, Apple would only say that "some" users were suffering difficulties, but would not admit to a specific percentage.