The real significance of Trayvon Martin's killing...
... is that there's not really much significance, as revealed in a Washington Post article referenced by iSteve.
The Official Narrative of course is that Trayvon Martin's death just underscores how black people everywhere are cowering in fear of white supremacists gunning them down as they walk home from the convenience store. When 'George Zimmerman' shoots 'Tray Tray' in 'cold blood' we have our Great White Defendant , instead of the exponentially more common thug-on-thug violence among those Americans who look like the son Obama never had. However, it turns out Zimmerman isn't exactly, well, white, and a prosecutor trying to prove the violent racial animus lurking beneath his brown-toned skin will have an uphill fight. Indeed, as the Post article reveals, in a lot of ways Zimmerman is really a poster child for "post-racial America," a man of mixed Jewish-Peruvian-African ancestry living in an ethnically diverse socio-economic sphere.
Zimmerman was also what some people in his father's demographic would call a shlemiel or a nebbish, hanging on to middle class status by his fingernails. The neighborhood experiences a rash of burglaries, and a civic-minded but not-very-bright George Zimmerman styles himself as the night watch, standing between his (financially underwater) neighborhood and anarchy. He confronts a young black man (which describes the six percent of the population who commit half the violent crimes), gets more than he bargains for, and fires his handgun. Manslaughter, maybe. Murder, ridiculous. It was a typically thoughtless, this-can't-end-well encounter between an armed man conscious of his tenuous social status and a high-T, high time-preference teenager.
As larger numbers of Meso-American and mestizo immigrants push into the only neighborhoods they can afford and attempt to better their lot, we can only expect such encounters to become more common. In sum, it's beginning to look like proximity killed Trayvon Martin, not racism.