Jon Stewart is making a movie in the middle east. He was aguest in Egypt on the equivalent show that he inspired over there "El-Bernameg":
Around the 10-11 minute point, he explains that speech even if insulting never causes injury. It may add insult to injury but never causes it. That is the American view of free speech.
In Canada, insult can also be sanctionable as the Supreme Court in Whatcott showed. Its ramifications were felt by a comedian, just the other day, when he and the comedy club owner were both fined for his offensive jokes.