OnTheSoapbox: I'm sorry, butt...
And so Zidane has apologised for head-butting Materazzi (read the BBC story here). But he has no regrets about his actions.
Perhaps I'm simple-minded, but can one be sorry and not sorry at the same time? If I think your "infraction" is great enough, do I have the "right" to retaliate with a strike of equal or greater force? Who is the final arbiter on which wrong is more wrong?
This was a physical attack within the context of a match governed by rules and a code of conduct. Who knows what Materazzi really said (although some claim it was a racial slur or worse). But whatever he said (which was wrong and I'm glad an investigation has started), how on earth can a retaliatory head butt be the "right" reaction in such a situation?
In my *personal* armchair critic opinion, a bigger man would've taken it up with the relevant authorities after the match. The slugger in me says the smarter man would've taken it up with a good old-fashioned insult trade-a-thon after the match :)
The golden rule I suppose is, act within the parameters of the rules or laws or generally accepted codes of conduct. These rules and guidelines are there for a purpose ... no ands, if or butts about it.
OK, I'll stop trying to sneak in a bad pun and get off this slippery soapbox now :)