The concept involves designing a notification or messaging system in such a way as to:
Reduce message clutter and avoid information overload, as in the case of blind duplicates of the same notification across multiple personal devices (e.g. mobile, tablet, desktop).
Improve the chances of a notification being received well and in context. In other words, it is personalized to the user's habits, location, time zone, and other factors that may influence whether the user appreciates the notification or not.
Enable the user to take immediate action in flow with the idea of real-time notifications, rather than dismiss the notification until later.
In essence, Smart Notifications aims to unify and make coherent all the real-time communications that a user is exposed to in their typical day-to-day. The actual techniques used to do this will necessarily vary in implementation, but a brief example might be by using a user's presence information to intelligently deliver a notification only to the device that the user is currently using, despite that they may be subscribed to the same notification channel on all their devices.