Before this gets any hotter - just wanted to say that physical depictions of holy figures in Islam is prohibited [wiki: Aniconism, Idolatry, Islamic Art, ...]. I personally don't watch any episode/movie/play with Jesus, Muhammad, Noah, Moses (PBUT) drawn or acted (I don't feel comfortable - Silly Me).
Religion is the only boundary that some have left. It encapsulates things as simple and beautiful as ethics and manners. What's wrong with a little of these?
freedom-of-expression (which should be held dearly) is not freedom to attack other's values.
I don't like Southpark (but I'll be waiting Futurama) :)