This website is finally up and running. For those who are interested, it's this weekend. The gallery location map is excellent.
We are going this afternoon; we went last year and it was wonderful -- and the weather is perfect again. You can get a map at their office on 1 rue Picabia and you can also buy a small square original art piece for 45 Euro submitted by one of the artists showcased. We got a couple last year. This is a really fun thing to do and it gets you into a party of the city not often touristed but which is quite interesting.