Here's the Florida statute under which George Zimmerman has been charged with second degree murder.  It's 782.04 2n: unpremeditated murder as a result of aggravated stalking.

This is defined as engaging in: 

willful, malicious and repeated following or harassing another with credible threats with the intent to place person in reasonable fear of death or bodily injury

A few observations:

1.  George Zimmerman is one of those rare stalkers who notifies the police before he commits his crime.

2.  According to what he tells the dispatcher, it is Trayvon Martin who first approaches him.  Only when Martin runs away does Zimmerman follow.  He does so between about 2:14 (when his truck door slams)  to about 2:29 on the tape, when he says "OK" in response to the advice not to follow the teen.   Even if the "OK" doesn't mean he complies, by 2:39 Martin has apparently disappeared.  (Zimmerman says "he ran" instead of "he's running.")  The aggravated stalking goes on for about 15 or 25 seconds, and is not very successful.

3.  We don't know what happened in the approximately 2 ½ minutes between the end of the phone call and the first 911 call.  Based on what Martin's father told reporters he had been told by the lead investigator, and on what Martin's anonymous girlfriend told reporters 23 days after the shooting, it's been suggested that there were two confrontations in the 2 ½ minute span, the first at Zimmerman's truck.  Whether or not words were exchanged, Zimmerman left his truck again and attempted to spot Martin.  He presumably did this in order to be able to let the police know the whereabouts of the suspicious character he had reported to them.  He expected an officer momentarily. 

This bit of stalking is no more successful than the first.  Martin surprises him as he's returning to the truck, asks, according to Zimmerman's testimony, "Do you have a f-ing problem?" and knocks him to the ground.

4.  Does Martin believe he is "in reasonable fear of death or bodily injury"?  If so, he does not return to the safety of the townhouse he's staying in.  From the time Martin is aware Zimmerman is watching him until the time the fight starts, he has over 5 minutes to go less than 1000 feet if he wants to evade the stalker.

Anyone has a right to approach a suspicious stranger in his own neighborhood and ask what he's doing there.  This is not stalking.

Aggravated stalking is a more appropriate description of the behavior of the media since mid-March.

It's also a fair characterization of the affidavit submitted by the State Attorney.