I really haven't paid attention to this at all (or at least as much as most people) but people don't actually think he shouldn't be charged, do they? Even if you think he's not guilty, let it go to trial.
On the matter of guilt or innocence, my belief is that the shooting wasn't justified in any manner. Even with a "Stand Your Ground" law, it is my opinion that he declined that right when he started pursuing Martin.
Obviously, no one has all the facts though.
You have put your finger on a salient point -- the reason this case blew up the way it did was because the shooter was, up till this point, not charged and the local police seemed to just take his statements at face value in spite of the fact there were significant problems with his story. One would think they would have tried a little harder when there was a dead body of an unarmed teenager.
Faux News and its affiliates, of course, are making a full-blown attempt to stir up white resentment. I suspect most of them have never had the experience of being accosted by the police or store security "driving while black," "walking while black" or "shopping while black."