Notifications hare handled in a similar way to iOS and the old Silverlight Studio.  On the far right of the screen above the Lead Origin icon, the Notification warning icon will appear on any lead with a pending notification.  In the red header the Notifications for all leads can be viewed.  As with the current system the Notifications apply to the user who is logged in, and are automatically created when certain actions occur such as Overdue Test Drives, or when customers reply to SMS or Emails.