I'm thinking he walks. After watching/reading some of the goings-on, I can't fathom how a jury doesn't walk away with some reasonable doubt. In my opinion, the whole case hinges on who threw the first punch.
If Zimmerman did, he was clearly the aggressor, and anything that happens after that punch is on him.
If Martin threw the first punch, than Zimmerman is well within his rights to defend himself.
We can argue all day on how the circumstances would have been different if Zimmerman hadn't gotten out of his vehicle. We can also argue about how the circumstances would have been different if Martin hadn't made the choice to confront Zimmerman.
Bottom line, regardless of the outcome from the trial, both men made poor decisions, and both men are stuck with life-altering repercussions-Martin lost his life, and Zimmerman, in a sense, lost his.
I'm guessing that in that split second before the fateful shot was fired, both men wished they had taken a different approach.
The verdict is in: Not Guilty.