The photo of an older Trayvon with gold “grills” is definitely him. Nobody is disputing that, unless there is an identical looking Trayvon with the same grills. The "gang signs" photo is of a Trayvon Martin from Savannah, GA. People probably made the mistake of thinking this was him because all his Facebook activity stopped around the time of the incident. The dead one goes by Trayvon Slimm martin on Facebook (a photo of him displaying the same gold grills is on his feed prior to the incident).
There are plenty of other real pictures of Trayvon Martin, from his MySpace and Twitter (where his ID is @NO_LIMIT_(*)(*)(*)(*)(*)). I believe that's where the other popular one came from.
The point is that the media is still showing 4 year old photos of Trayvon from when he was 13, when in reality he was almost an adult. This is confirmed on his (now unused) MySpace where photos of him in that T-shirt are dated 2008.
Whether one of the circulating photos is fake or not, it does not change the manipulation and bias the media is guilty of by showing a photo of a child, not of a late teen with gold grills and tattoos.
Nobody is implying that this means that Trayvon deserved to die, but people are looking at a picture of a 13 year old and thinking it is inconceivable that he could have attacked Zimmerman to the point he feared for his life. So it is manipulating public opinion on the issue.
A fairer comparison would be a stranger following you, you turning around, punching him in the face, jumping on top of him, pounding his head into the ground, and then the stranger manages to get his gun out and shoots you, and claims self defense.
The question then is whether you believe that
a) someone following you justifies punching them in the face and pounding their head into the cement
b) someone on top of you pounding your head on the concrete justifies you shooting them
Zimmerman receiving a beat down and Martin getting shot could both have been advoided at different points. It depends whether Zimmerman did something other than just following Martin to provoke the attack, and whether Zimmerman has genuine reason to fear for his life when he shot Martin (I think it's safe to say someone on top of you has the advantage, and could easily get your gun if you didn't get it first).
This is the same link from the 'New York' Trayvon FB site - his page says he commented on a link, right above the posted pic of him in his orange shorts and his posing. Immediately under his comment, there is a conversation regarding whether or not he is the Trayvon Martin from Florida (spoiler: He is not)
Admitted fake. One of the original posters has issued an apology.