To answer the question
What would have happened, had Martin been white, and Zimmerman black?
I heard about this (or a story similar to this, as I couldn't remember the names, so I did a google search) on the radio, as an example of another jury, looking at the facts, and deciding on the merits of the case. I know the details are not identical, but you can read the article, and make your own decision on the similarities, but with the races reversed. For clarity, Scott was a black man who shot Cervini, a white teenager, whom he suspected of stealing.
Note some of the comments from others in the article:
"How can this happen to a beautiful, sweet child like that?” asked Cervini’s aunt Carol Cervini.
Scott says he acted in self defense when he confronted Cervini and two others saying they were stealing from neighbors cars
Cervini's family members say justice wasn't served. They say Christopher was murdered in cold blood, that he'd never been in trouble and Scott acted as judge, jury and executioner.
Sounds very similar, that it was a tragedy, that ended in the shooter being found not guilty due to self defense.