Apple appears to be testing a notification system for the web interface of its iCloud service, as evidenced by a placeholder notification appearing for some users upon logging in to iCloud.com.
While the placeholder nature of the message indicates that its visibility to the general public is likely in error, adopting notifications for iCloud would unify the experience between iOS 5 and the forthcoming OS X Mountain Lion, both of which feature a “Notification Center,” alerting users to important messages and events.
It’s also possible that Apple envisions iCloud.com notifications to substitute for desktop notifications for iCloud users who do not have a Mac. After all, in the age of iDevices, many of Apple’s customers do not have a Mac and won’t receive the benefit of Mountain Lion’s notifications.
For now, the notification remains at the top of the page, even as the user switches between the various sections of the service, and only disappears when dismissed via the “x” to the right of the message. Once dismissed, it does not reappear upon subsequent log-ins.