Show a "Now Playing" iTunes Notification in the Mac OS X Lion Dock

Using a defaults write command, the iTunes Dock icon can be set to display a "Now Playing" song and artist pop-up that transitions in and out and music starts. It's a nice addition, particularly if you're playing songs from a shared network playlist and have iTunes hidden in the background.

Enable the iTunes song & artist Dock icon popup:
Open the Terminal in /Applications/Utilities/ and type the following:

Start playing a song in iTunes to see the notification appear, it'll disappear automatically and then reappear briefly anytime a new song starts.

Disable the iTunes song & artist Dock icon popup:
Open the Terminal in /Applications/Utilities/ and type the following:

Note: This only works in Mac OS X Lion 10.7.