Apple has confirmed the service interruption on its iCloud System Status webpage, noting that some iMessage and FaceTime users are unable to send messages or make video calls. The root of the problem is unknown at this time.
Tuesday's troubles add to a list of sporadic iCloud service outages that have cropped up recently. The issues are usually resolved within one to two hours.
Most recently, Apple's iCloud account authentication system went down immediately after the company rolled out the OS X 10.8.3 maintenance update, causing some users to be left without a number of services.
Update: As of 5:20 p.m. PST, all issues have been resolved. The outage lasted for a little over five hours.