A lot of people are commenting that this is not "the first". Who cares?
It is not the first but, for one, it will be the first that will be heard of by people living far from it. Folks get over this: there are more international reporters in Paris than in all of the other quoted cities I've seen so far combined.
More importantly, given the monthly price, it seems to be a lot more geared to the occasional short trip. We (me+wife) used a car pool system in The Netherlands for a couple of years. The trick with it was that the monthly fees were so high that it only made financial sense if you needed a car for a couple of hours a week, every week.
The trick of this Parisian car system is that it costs a small amount to be part of it, that should allow (I hope) for people without constant need for a car to make use of it. It should also go a long way towards giving car-pooling more global visibility.
FWIW, The Netherlands also had an early bicycle sharing program in Amsterdam in the 70s that was a disaster, perhaps they were also the first in it, but again, who cares? It did not work, and was cancelled. France had a huge success with large-scale bicycle sharing programs which spread through all its major cities, and they work. The Velib in Paris (also not the first) works in every way it should, and given the amount of tourists that come to Paris, it is probably the most visible in the planet (i.e. it is the one that spreads the good news, and helps to convince the sceptics).