OS X and Growl notifications are AppleScriptable and great for displaying user-defined text, but not so hot for user-defined images. OS X can only display the sending application’s icon, and Growl no longer accepts raw iTunes artwork image data or regular image files.

Growl’s iTunes limitation can be overcome by converting an iTunes track’s raw artwork image data into a TIFF file that can be read and passed to Growl:

tell application “iTunes” to set _rawData to raw data of artwork 1 of current track

set _startupDisk to (path to startup disk as text)

set _tempTiffFile to (open for access file (_star …

Source: Mac OSX Hints