More progress! Notifications are basically just an activity stream. So CB Activity is utilizing the existing functionality to provide the notifications. You can have notifications for anything you like using CB Auto Actions, but there's a few that have built in display parsing code to make this a bit nicer. Check out the current progress below.
Currently notification display is processed for likes, tags, and comments for activity, comments, and CB Gallery media. GJ notification processing is next on the list followed by a button icon that displays new notification could and on-click ajax display of the most recent notifications. A Joomla menu endpoint is also available to quickly reach notifications though a menu item.