Never mind, I think I got it figured out:
http://www.getmein.com/venues/le-zenith-paris.html
http://listentheworld.wordpress.com/2008/02/25/larcenciel-tickets-on-sale/
(scroll down to the bottom where it shows "standing," which is apparently "cat 2 debout placement libre")
Sounds like standing is the way to go! Soon as our flights are booked, tickets are next...
So anyone planning to go to the Paris show?!