It's not a retrial but a reappeal. The last one which freed the accused being flawed and to some extent even illegal so it has to be done again.
For example; the defence were incredibly allowed to reduce the scene of the crime to one room in isolation from the rest of the flat, which logically is part of the crime scene as well. This allowed the defence to cherry pick evidence (DNA)
* that they then attacked. It was also illegal for the judge not to allow the DNA testing again and it was pointed out that the appeal judges use of vocabulary pointed to a not guilty premise, like he had decided beforehand that they were innocent. That is malpractice.
Anyone interested in the case should read this thread from the beginning or consult this web, which has translations of the legal documents, reports, powerpoints and roundups of all the evidence that put everything into perspective:
http://truejustice.org/ee/index.php
As for posts about witches and stuff, that is just typical of defenders of the Knox camp, as they persistently choose to focus on the gossipy stuff, as though it were a defence, and avoid talking about the hard facts, such as evidence, etc...
* From the above website:
two consultants, illegally appointed and ill qualified, tried to make out there was possible contamination. They proved nothing. They ADMITTED Meredith’s DNA was on the big knife and that Sollecito’s DNA was on the bra clasp. There was lots of other incriminating DNA evidence outside Meredith’s door.