Monsieur Chat

So Johnny Strike, from Seen Any Good Films Lately turned me on to Monsieur Chat after he had read my blog on Space Invader and said it was similar to the "Monsieur Chat" phenomenon that has taken place mostly in Paris but also other European cities. "Monsieur Chat" or just M Chat( as in J. Lo or P. Diddy) is a graffiti cat that had begun showing up on the sides of buildings following the 9/11 terrorist attacks.

The most notable feature of M Chat is its large Cheshire Cat grin. M Chat is often depicted in various poses and sometimes is accompanied by the tagline M. CHAT in small letters. The graffiti artist or artists of M Chat have so far remained anonymous.
Do you know who they are?
M Chat Flickr group
Wikipedia article
monsieurchat.free.fr: A site in French documenting appearances of the graffiti cat