You know who started that petition? Or at least inspired it?
Stevie Wonder.
He was giving a concert in Canada when the verdict came down, and spent 15 or 20 minutes talking about it on stage, and said he will boycott Florida, and any other state with similar laws, until those laws are changed. In addition for Florida, 25 other states have enacted "Shoot First" (or Stand Your Ground) laws, and 7 others have laws permitting virtually the same thing via a combination of statues, judicial decisions and jury instructions.
The Florida-style Shoot First Law allows the shooter to escape liability in a pretrial hearing, and prevents law enforcement from arresting the shooter unless there is actual probable cause that the use of force was unlawful (which is why Zimmerman wasn't arrested the night of the shooting). The other states with the de facto same (VA, IL, NM, ID, WA OR, CA) don't allow the shooter these protections, and the shooter will almost certainly be arrested even if it's not clear whether or not the shooting was justified, which will get sorted out in pretrial or at trial. But the justifiable self-defense statues still rule unless prosecutors can prove unlawful intent by the shooter (they have to prove it wasn't self-defense, rather than the shooter having to prove it was).
In OH, WI, ND and MO, the Shoot First laws only apply if the shooter is in a vehicle, rather than on foot in public (which, I think, it retarded).
Ironically, Zimmerman never invoked the Stand Your Ground law in his defense at trial.
Florida was the first state to enact the law specifically. Others quickly followed. The NRA was the primary supporter of the law, in addition to most private citizens. Law enforcement was pretty the only group opposed to it (other than those who think guns can be eradicated from the planet).
Since Florida's enactment of the law in 2005, the number of justifiable homicides have tripled in the state (2005-2010), which opponents cite as reason to repeal the law. However, if you aren't Forced to Flee and can defend yourself, it stands to reason that the numbers would rise. During the same period, the number of violent crimes has dropped by more than fifty percent, something which opponents conveniently ignore. Other states with the same laws have seen similar numbers as Florida.
