Charlie Hebdo is a long-running, hard-biting, often offensive leftist satirical weekly, with caricatures I think you couldn't see in the USA (such, I don't know, as Shiraq being "persuaded" to be candidate for the 2002 presidential elections by being fellated and sodomized by Sarko and I-don't-remember-who, while doing the double "V for victory", you see the type).
I used to read them back in the olden days... they ARE funny!
Redaction is partaged between idiotarian and anti-idiotarian, apparently the latter have won.
Reason why they're antimuslim is because they're aggressively atheist and opposed to organized religion.
I've bought this issue, which apparently sells very well, well beyond usual runs, and I've got mixed feelings; editorials are pretty clear on where they stand and pull no punches, but they also shoot at "others fundamentalisms" (read : jewish and christian), so I feel they miss the point a little bit, like the Mo' cover, which doesn't acknowledge IMHO the "rotten roots" of islam as established by the Prophet(tm).
Cover of this week edition
Old cartoon from the 2002 nigerian beauty contest riots (already an organized wave of letter, threats,... at the time).
*Miss potatoes bag election, organized by Muhammad*, old Mo' : "I choose the Belle-de-Fontenay" (Miss France organizer).
*No amalgam*, "Moderate islam/Radical islam" (july 2005)
More Charlie hebdo pics, from Google, so you can get an idea of the mag.