The updater brings the device's output into line with local French law requiring audio devices of that type to deliver a maximum 100dB of sound. In their natural state, iPods deliver 104dB.
The difference in sound output levels forced Apple to withdraw iPods from sale in France last week. At that time, the company promised a software update to bring its product into line with the legislation.
The 5.1MB update is available for download. It requires version 1.2.1 of the iPod software.