I recall there were comments last year that Bottles were being banned, and some people reported early on in the week this was accurate. We arrived on the Friday and saw that either the reports were wrong, or the rules had been relaxed and gone back to normal. We were able to bring glass bottled beer into the circuit where we camp, and we were not stopped from walking around drinking from glass bottles.
It is my belief that without the volumes of beer sold, Le Mans would not quite have the same atmosphere, and given the Economic situation in the EU right now, I don't think the French will change the status quo right now. It would be very brave and potentially foolish for them to do so.
This year, I'll again be heading down on the Friday, so I'll be checking the updates from the campsites during the week. 5th Anniversary this year. :-)