No, there isn't one looking at this case now and there may never be a grand jury for this reason...
Tough-minded prosecutor in spotlight on Trayvon Martin case“I always lean towards moving forward without needing the grand jury in a case like this,” Angela Corey, the state attorney assigned to the case by Gov. Rick Scott, told The Herald/Times. “I foresee us being able to make a decision, and move on it on our own.”
She can move on it without a grand jury and she can also dismiss it and that should be the end of it as far as the state of Florida is concerned.
It certainly doesn’t have to go to a grand jury, but I thought I had read that the case was going in front of a grand jury in response to the pressure to hang Zimmerman. Of course, an even semi-competent prosecutor can usually get a grand jury to indict a ham sandwich, so a grand jury indictment doesn’t necescarrily mean much.