While mucking around in iTunes I noticed that when I clicked on some of the songs in my iTunes library, arrows appeared on either side of the Selected Song entry that is revealed when you click the Show Artwork button. Because I'm a natural button pusher (versus a born lever puller), I gave these arrows a click.
Wouldn't you know it, clicking these arrows revealed that these songs had more than one piece of artwork associated with them (as confirmed by pressing Command-I and clicking the resulting Artwork tab). "Suppose," I thought, "I dragged multiple jpeg images into the album field. Would all these images be attached to a song?"
As a matter of fact, yes, they would.
So what earthly good is this bit of trivia? Other than making your song files larger, it might satisfy the kind of music geek who wants a song to bear the differing covers of the American and British releases of Elvis Costello's This Year's Model (and yes, I'm exactly that kind of music geek). Or, if you're the sort of person who marks his underwear with an indelible Sharpie, nothing says "Mine! Mine! Mine!" quite like a scanned signature dragged into the Album field of all the songs in your iTunes library.