One of the new "features" in the latest line of iPods—classic, touch and nano—is a "cryptographic checksum" in the song database that won't let you sync with any application besides iTunes. Since there's no iTunes for Linux, if you're running with Tux, you ain't running with your iPod.
Using a third party app (such as Winamp in Windows as well) to unlock or modify the database file (i.e., load up or sync your iPod), will make your iPod tell you the number of songs on it is a big, fat zero. Work's started on a hack, but it'd be nicer if Apple fixed this themselves. You know, instead of totally cutting off a not-insignificant swath of their customers. [ipodminusitunes via Boing Boing]