Zimmerman was probably being a blowhard dickhead, but that doesn't warrant a violent reaction.
A very similar situation happened to me when I was a kid. I was driving through a friend's neighborhood with the friend who lived there (female) and two other friends (male and female).
Some dude started following us in his car, so I drove around a few turns to see if he really was following us. We didn't know what the hell he was doing or why he was following us but he was being a major prick about it (practically trying to run us off the road).
Eventually he cornered us by blocking off the road with his car. He jumped out of his car and came storming over to my car. I'm sure the conversation between us went very similar to Zimmerman and Martin.
He said "what are you doing here?"
I replied "she lives here! Why are you following us?"
We told him what street she lived on and he realized he knew the name and IMMEDIATELY felt like a huge asshole and apologized repeatedly. Apparently there had been someone driving through the area stealing kid's bikes...
Moral of the story is...we acted like civilized humans and it ended in a civilized manner.
The guy felt like a shithead (because he was acting like one) and got shit later from his wife and my friend's (the girl who lived there) dad. I'm sure he felt like an ass in front of most of the neighborhood for a while.
A lot of people in neighborhoods do dumb shit. I was actually sitting on a side road in a neighborhood once, and was on the phone with my Ex-Wife. I was actually 3 houses down from a girl I was picking up to go out with.
This guy comes over to my car and starts talking asking me what I'm doing here. I tell him I'm on the phone with my ex wife and about to pick up someone and I'll be off the phone in a second.
He starts talking something about some creeper dude being in the neighborhood and how he's going to call the cops. I told him to go ahead. I don't care. I'm just sitting in my car. Which as far as I'm aware isn't a crime.
He gets huffy rides off... Straight to the house where I was picking up the girl.
I drive up and the girls brother is talking to the dude and the dude gets all flustered and starts apologizing.
Sure, people do dumb shit, but if you're also not a dumb shit, you can usually get through it.
Shit escalating to a fucking gun fight is goddam ridiculous.
I've been saying this from the start... Zimmerman should have been charged with Manslaughter and is an idiot. Trayvon is unfortunately a dead idiot. Zimmerman should never be allowed to carry a firearm ever again because he's an idiot and he should go to prison for some time.
BUT HE WON'T
Because he was charged with MURDER and not the appropriate crime.