Most people commonly understand jury trials to determine the innocence or guilt of the accused. Such is not the case however. The jury can return one of two substantive verdicts: guilty and not guilty. Not guilty is not synonmous with innocence. It simply means that the prosecutor has failed to prove his case.
In the United States appeals are limited to questions of law not fact. Whatever facts the jury at trial found stand. The appeal searches out errors of a legal nature in what happened during the trial: a failure by the judge to properly instruct the jury, ineffective assistance of counsel, lack of due process, etc. In Italy the appeals court reviews both the facts and the evidence, meaning it can disbelieve the testimony of certain witnesses or find that the facts proven are not really facts.
That brings us to our subject. If Amanda Knox had been tried and found guilty in the US in all likelihood she would have lost her appeal. She is fortunate to have been accused in Italy where the appeals process even allows her to make an impassioned plea against her conviction. But even in Italy where the appeals court found errors in the collection of foresenic evidence, her victory does not prove her innocence, any more than O.J. Simpson's acquittal means he didn't murder his wife.
Amanda now stands to make millions off her ordeal and she will assert her innocence. That's her right. But no court has found her innocent of this crime. The most she can say of the legal proceedings is that sloppy police work undermined the prosecutions case. She still has certain things to explain: why she confessed before the first trial, how she knew details of the crime that only the murderer or his companion would know.
She certainly looks innocent with her youthful beauty, and her weeping protestations of suffering. Looks do not establish innocence however. Now that she has been released we will probably never know who killed her roommate.
Oh yes, someone is in jail for it: the only black man the police could find within miles of the crime. Isn't that just like the US? Round up the blacks while beauty goes free.