Will Fisher writes "New iPods will no longer be able to work with Linux. iTunes now writes some kind of hash (SHA1, md5?) to the iPod database which new iPods check against. If this check fails then the iPod reports that it contains 0 songs. This appears to be protection against 3rd party applications writing out their own databases. We haven't found out how to generate our own valid hashes (but we do know the hash includes the database itself, and possibly the iPod serial number), and are looking for help."