The rules cover everyone driving in France, so if you are coming on holiday here in the next few weeks then make sure you have at least one, preferably two, in your car.
The breathalysers have to include the NF graphic to show they are compliant with the French regulations, a quick look at some popular online shops showed they had the recognised equipment in stock.
One thing to look out for is that the breathalyser is valid to use as there is a 'best before' date on them.
The French authorities have also decided that drivers will be advised of the legislation from July until 1 November 2012, following which fines will be handed out if drivers are not in possession of a kit.
Full text: Décret n° 2012-284 du 28 février 2012 relatif à la possession obligatoire d'un éthylotest par le conducteur d'un véhicule terrestre à moteur
Download Décret n° 2012-284 (.pdf)