And so, to the now (in)famous Zinedine headbutt.
Personally, I laughed myself silly watching re-runs of the thing on TV, and continue to maintain that it was an act of comic genius (as I argue in the comments here). I mean, can you imagine a wackier and more unpredictable way of ending a career? It's positively inspirational. The day I finally get my PhD my advisor had better be wearing a sternum guard.
I'm even more amused by the reaction of Zidane fans. First, there's this whole racial sledging thing. Everywhere I look people are going around speculating on what Materazzi must have said to Zidane to provoke the headbutt. Aside from the fact that at this point this is all unproven hearsay (even if Zidane does finally come through with a statement, I don't see any reason why we have to take his word against Materazzi's), I'm amazed that anyone would think that anything Materazzi might have said was justification for Zidane's actions. The argument is not, as some people have suggested, that Zidane should not have reacted because it was the World Cup Final and he had a critical role to play. The argument is that, outside of Dharmendra movies and Shiv Sena Headquarters, it is not okay to respond to things you percieve as insulting with physical violence. That argument applies as much to Zidane as it does to the rioters protesting the Danish cartoons or the 'desecration' of Mrs. Thackeray's statue. Physically assaulting someone on the playing field because they say something insulting is behaviour better suited to eight year olds. In a civilised society we don't responds to words with fists. Or headbutts.
I'm also amused by the convenient fiction (implicit in much of the moaning about Zidane's actions) that Zidane's exit was the reason the French side lost the match. It's certainly a wonderful face saving device, isn't it? The fiction writer in me is almost tempted to speculate that maybe the very purpose of the headbutt was to get Zidane sent off so the French would have a ready excuse for losing.
Finally, I can't help being a little curious about the headbutt per se. Who responds to insults with headbutts? Punches, yes. Kicks, possibly. But headbutts? Is this a cultural thing? Are there societies out there where the headbutt is the ubiquitous form of social assault? Do people actually go around saying "Say one more word and I'll headbutt you in the sternum"? Are there martial arts movies where the hero and villain fight by exchanging headbutts? Has Zidane watched too many Animal Planet specials on the mating rituals of antelopes?
Or was Zidane, perhaps, concerned about using his hands in a football game? Because THAT would be a foul?
 The desire to escape being insulted is, of course, the principle reason that the French don't speak anything but their own language - that way they don't know what the English are saying about them. You could always try insulting a Frenchman in French, but the odds that you'll actually pronounce it right are so low that it's not a serious threat.