People need to stop acting like they know what happened that night. Was Zimmerman a good guy attacked by a thug who defended himself? Was he a vigilante who gunned down someone without justification? Based on what we know from media reports, either is possible. Let the evidence come in at trial, and determine reasonable doubt from there. Then let the evidence come in at the inevitable civil suit, and examine it based on the lower preponderance of the evidence standard.
If I had to bet, right now, I say he gets a criminal verdict in his favor and a civil verdict against him, just based on the differing standards. But I don't know.