And the winner is...
Massilia Sound System - "Massilia fai avans"
French reggae music, although the band tends to perform in the minority Occitan language, rather than French.
The quirk here is that there wasn't a special playlist set up to reach the number. This was partly because I didn't know precisely where I was over the weekend, but mainly because I'm trying to listen to all the good music I know before I leave so I can get the songs onto my iPod.
So the French reggae joins two other songs as milestone tracks. They are:
Sabaton - "Nuclear Attack" (5000)
Roger Cicero - "Frauen Regier'n Die Welt" (10000)