BoingBoing writes, The latest iPods have a cryptographic “checksum” in their song databases that prevents third-party applications from synching with the portable music players. This means that iPods can no longer be used with operating systems where iTunes doesn’t exist — like Linux, where gtkpod and Amarok are common free tools used by iPod owners to load their players. Notice that this has nothing to do with piracy — this is about Apple limiting the choices available to people who buy their iPod hardware.