It is now being reported that Free (the ISP in question) will deactivate the automatic blockage. »www.lefigaro.fr/hightech/2013/01 ··· iser.php
Two interesting facts:
(1) Free is reported to be "in negotiations" with Google. So perhaps this was just a gambit to get Google to pay them for access to their network or have all of Google's advertising capabilities blocked.
(2) Free has been asked to explain their actions to the France's Minister de l'Économie Numérique. So as is the case in many things, the government will intervene and decide what is "free" commerce and what is not.
Both of those facts are perhaps even more troubling than the ad blockage.