It's not the iPod they care about, though... it's the approximately 30 cents per songs they make selling songs on iTunes. for most songs, they're making about ten cents for every megabyte they transfer, with no rent on stores to pay, no employees other than the developers, no shipping costs, and the music comes to them already pre-encoded, so they don't even have to "order" new titles or anything.
in march, they had already sold 350 million songs. that's approximately $105 million in revenue for running a website on bandwidth they probably already had, and a figure that is only going to accelerate, especially with the new iPod.
edit: revenue may be higher for the iPods themselves, but i'm sure they cost WAY more to develop than the iTunes application and website.