For those who aren't aware (such as Leonard Shapiro of the Washington Post), the sport of mixed martial arts is not a no-holds barred street fight, but a sport with rules and a referee who enforces them.
One of the rules is that a fighter can't strike with an elbow in a downward motion and can't strike an opponent in the back of the head. As you can see in the above photo, Malaipet Sitprapom did both of those things to Thomas Denny in Friday night's EliteXC event in Santa Ynez, California, leading to Denny winning by disqualification.
A fight that ends in a DQ is always a disappointment for the fans, but it may actually be a good thing for the sport that EliteXC -- which is about to get a huge boost in publicity when it has its first show on CBS in May -- had a bout end in this way.
There are still people out there who really don't get what MMA is, who assume that there would be no such thing as a disqualification because there's no such thing as a rulebook, other than "last man standing wins." If those people hear about this disqualification, perhaps they'll actually take the time to learn something about the sport before they trash it.