Head-butting Materazzi was a bad idea. But until we know, or have better evidence of, what was said, to judge it 'unpardonable' is simply premature. (Especially since Materazzi has previous.*)
As for Zizou's career, apotheosis came in 1998. Indeed, when all's said and done, he twice led goodish teams to World Cup finals, and managed to win one of them almost single-handedly. He's scored as many goals in World Cup Final matches as Pele has, is easily the best European player since Cruyff, and is responsible for the best goal ever to win a Champions League Final. Merci Zizou!