iCloud encountered an error while trying to connect to the server
Attempting to access iCloud through System Preferences on iOS also gives you a connectivity error. Mail and some other iCloud services are also not accessible through iOS, although some applications like Calendar work just fine. Reports across social media also confirm iCloud issues.
Oddly enough, Apple's own system status page indicates there are no issues with any Apple services, including iCloud. Just two week ago, iCloud also had a widespread outage that interrupted the service for many.
Let us know how iCloud is working for you in the comments below...
Update: Services seem to be fully restored
Please follow iClarified on Twitter, Facebook, Google+, or RSS for updates.