9to5Mac reports:
The feature is a toggle accessible at the top of Notification Center that allows users to block incoming alerts and banners. The feature is very important for those who look to focus entirely on the content they are currently working on and do not want to be bothered by new emails, iMessages, calendar alerts, or other types of alerts.
When the feature is active, the norman Notification Center dot in the menu bar changes to a moon. While it’s great that Apple appears to be bringing this feature to Mountain Lion, I can’t help but wonder why it hasn’t been added to iOS! Perhaps this is a sign of things to come in iOS 6?