The map of Paris voting is quite interesting. Hollande took the western part of the city, including the wealthiest arrondissements, while Aubry took the east, running up some of her highest percentages in the most populaire districts. Montebourg did somewhat better in the east than in the west as well, but he had respectable scores in the west. Valls did best in the 16th Arrdt.
So, while it's foolish to say that Martine Aubry was the candidate of le peuple de gauche, she did outpoll Hollande in areas with strong working-class and issue de l'immigration representation.