A company called CodeWeavers has a new version of its product available that will allow the iTunes software to run on Linux. I wouldn't imagine it'd be all that difficult to port, actually, seeing as how the original version was made for OSX, which is based on a BSD core...

"The company said CrossOver Office 3.1 adds support for the jukebox and music download software. The version is currently in preview form and is being made available only to existing CrossOver Office customers."