It has been confirmed that Osama was unarmed..... He was apparently resisting arrest (or whatever). So what did the Special Forces do next....... Shoot him in the head!
Sorry but that was wrong!
As with many people you have the notion in your head that combat should be fair. Ideally Osama and Obama should meet at dawn and battle with fences until one opponent draws first blood on the other. The loser then surrenders to the victors terms, they bow to one another and go on their way. As silly as this sounds many people use such guidelines to judge whether a given combat situation was fair or not. This is fantasy.
The Reality:
Real combat is anything but fair. It is about getting the advantage over the opponent and pressing it home. Just because the enemy is at your mercy doesn't mean he gets a get out of jail free card. Examples:
When soldiers charge an enemy line and break it they will just as often kill the guys in the foxholes, even if they throw down arms and wave white flags. This isn't murder or a warcrime.
During the first Gulf War I think we all know the famous image of the Highway of Death. Fleeing Iraqi soldiers for the most part in comandeered civilian vehicles were straffed by jets and helicopters without mercy. The allies had almost total superiority and the enemy was broken and fleeing.
At the end of WWII when Berlin was surrounded the war was basically over and Germany was no longer a threat to anyone. The allies pressed home and finished them off completely.
Near the end the Japanaese had lost most of their navy, the surrounding islands taken and they were all but defeated. The allies could have stalled for peace talks, but they nuked them into full submission anyways.
The point is that war is not fair. When the enemy is down you don't suddenly stop attacking. You kick him in the face as he is laying there so to speak.
The western nations declared a war on terrorists long ago. What that really means is that your life as the enemy becomes real uncertain. Whether you live or die basically comes down to the whim of the guy with a gun pointed at you.
The balance in the system is the huge military court system like in the TV series JAG. I'm very sure that the guy who pulled the trigger on Osama will have some hard questions to answer.