@hawkeye10,
Actually, people are usually likely to act morally when they've just been instructed to do so.
Numerous studies support this. People behave more morally after having washed their hands, after having been asked to recall the 10 commandments, etc.
Plus, I'm not sure that folks would be willing to blatantly display their racism by repeatedly voting for acquittal, and having to face the other jurors. (Assuming an 11-to-1 split, as you suggested; I hope that Zimmerman gets a scrupulously fair trial so that they can make the conviction stick.)
Finally, a hung jury does not result in an acquittal, it results in a mistrial, and the defendant can be tried again.
As an aside... no matter what the police may feel on the matter, I'm encouraged that safeguards are in place so that the incident is getting reviewed.