“Now Playing” iTunes notifications is by default hidden on Mac OS X Lion 10.7 or later, but through applying a tweak that could get enabled, now if you want to enable or disable this feature on your Lion Mac computer then guide below will help you to do so.
Enable “Now Playing” iTunes Notifications in OS X Lion
Step-1
Quit iTunes if its opened
Step-2
Go to “Finder” > “Applications” > “Utilities” to launch Terminal
Step-3
Type and execute these commands one after one in Terminal window
defaults write com.apple.dock itunes-notifications -bool TRUE
defaults write com.apple.dock notification-always-show-image -bool TRUE
killall Dock
Step-4
You will observe “Now Playing” Notifications appear above iTunes in dock when you will play any media file
Disable “Now Playing” iTunes Notifications in OS X Lion
Step-1
Quit iTunes
Step-2
Open Terminal and execute following commands one after one and that’s it
defaults write com.apple.dock itunes-notifications -bool FALSE
defaults write com.apple.dock notification-always-show-image -bool FALSE
killall Dock