A variety of third-party utilities can display details about the track that's currently playing in iTunes. But Hints reader Keir-thomas discovered a secret preference setting built into OS X Lion that allows song notifications to pop up over the iTunes Dock icon. Here’s how to enable them:
First, quit iTunes if it’s already running. Fire up Terminal (from /Applications/Utilities/) and paste in the following command, then hit Return:
defaults write com.apple.dock itunes-notifications -bool TRUE;killall Dock
The first part of that command turns on the Dock’s ability to display iTunes notifications; the second part restarts your Dock. (That restart may take a couple of seconds.)
Now, relaunch iTunes, select a track, and press play. Down in the Dock, you’ll see a brief notification with the song’s name and artist. The notification will appear whenever the track changes, regardless of the app you’re currently using; it will then fade away on its own.
If you decide you don't like the notifications, you can get rid of them by issuing the same command, but replacing