This is not a rumor: the notification history is a true feature from Android 4.3, although they don’t make any mention of it in their What’s New page.
The following steps will allow you to take advantage from the Notification History in a vanilla Android Jelly Bean 4.3:
- Go to your app drawer, then tap the Widgets tab. Scroll until you reach Settings shortcut (1×1) widget.
- Drag and drop this widget to your home screen.
- You’ll see a screen where you can select the type of settings this shortcut will open. Select Notifications.
- The shortcut Notifications will be in your home screen, tap it.
- The screen Notifications shows the notification history we are talking about. In this screen currently active notifications appear in full intensity, while dismissed ones are dimmed.
- Tapping in each notification from this screen will open the corresponding App info screen, where you’ll be able to toggle the option Show notifications as you wish.
- Remember: if you turn off notifications for an app, its icon will disappear from the status bar, all its notifications will be dimmed in the Notification history screen, and you may miss important notifications about this app from now on. Only do this if you are completely sure.