
Here's an article from Italy which gives an update on the case, as provided by Seattle reporter Candace Dempsey:
The ‘collapse’ of the charges at the appeal court.
By Giangavino Sulas
 April 2011, Perugia.
The scientific proof,  finally entrusted to experts nominated by the  appeals court and not just to the police, is deteriorating and opens up  disturbing questions about the procedures used. The witnesses, who when  they were not drug addicts (like Hekuran Kokomani and Antonio Curatolo),  have problems of deafness, of physical as well as mental health serious  enough to be hospitalized in the psychiatric department. (That is the  case with Nara Capezzali).
 This is the Perugia appeals court for the murder of the British  student Meredith Kercher. Before the bar are two suspects and on the  bench a good three prosecutors (a public prosecutor and two deputy  prosecutors). A number worthy of a Cosa Nostra super trial. Evidently  there are a few problems. And the problems unfailingly emerge.
 If  Meredith’s bra clasp, on which the prosecutor maintains is  revealed the DNA of Raffaele Sollecito, is now rusted and no longer  capable of being analyzed by the experts entrusted by the appeals court,  and  if the only witness who claims to have seen Amanda and Raffaele  together the night of the crime has changed versions, advancing a  “vision” of the previous night, what remains against Raffaele Sollecito,  the young man from Puglia?
  And what remains against Amanda if, always according to the experts,  the amount of biological material found on on the knife, the presumed  crime weapon, is a level too low to be able to reveal the genetic code?  Recall that this is the biological material from which the forensic  analyst extracted the DNA of Meredith (on the tip of the blade) and of  Amanda (on the handle.)
 On the blade there is no trace of bleach
The experts added as well another particular: there was no  trace of bleach on that knife. Then it had never been washed to clean  the traces as maintained by the forensic police. The only proofs against  the two young people have been cleaned away, but Amanda and Raffaele  remain in prison after three and a half years. The young man of Puglia  has celebrated his fourth consecutive birthday in a cell.
 March 26, 2001 was the day for Antonio Curatolo, the homeless man  who, since he decided to follow the way of Christ (he defines himself as  a Christian anarchist but admitted to make regular use of heroin and  other drugs) spends his days and his nights on a Piazza Grimana bench,  in front of the University for Foreigners. He appeared before the court  because the lawyer Luca Maori, Sollecito’s defense lawyer, discovered a  few too many holes in the testimony given by the homeless man to  prosecutor Giuliano Mignini, six months after the crime.
  Curatolo–who in the last few years in Perugia helped police resolve  two heinous crimes thanks to his timely presence on the spot where they  occurred–went to court to reveal that on the night of November 1st, 2007  he had noted, from 9:30 p.m until 11:30 p.m., Amanda and Raffaele in  Piazza Grimana speaking animatedly. And he tied his memory to the  presence of the shuttle buses that at that hour carry young people to  the various discos outside of Perugia.
 Testimony that destroyed the alibis of the two young people, who’ve  always said that they spent the night of Nov. 1 watching a movie  together. But there was something wrong with seeing buses on that night.  In fact, the owners of the various discos, from Giorgio Brughini,  father of Marco Materazzi, to the director of “siae di Perugia,”  came  to court to say that on the night of November 1, the night after  Halloween, all their businesses were closed and the buses stayed in the  garage. A solid blow to the prosecution, which quickly removed the  tramp. And Curatolo had come into court accompanied by a prison guard.
 The homeless man and the experts
 He’s serving a sentence of one year and a half in prison for selling  cocaine. And in November he can expect another trial for drug dealing.
 Before the appeals court judges overturned his deposition: “It was  Oct. 31 when I saw Amanda and Raffaele. I remember all the kids were in  costume.” Clear reference to the night of Halloween. End of  testimony. Curatolo has gone back to prison.
  He’s not going to solve the third murder in Perugia. Carla  Vecchiotti and Stefano Conti, professors at Sapienza University in Rome,  are the experts chosen by appeals court judge Claudio Pratillo Hellman  when he decided to reopen the investigation and to appoint non-partisan  experts because of too many obscurities in the courtroom.
 In the first trial, independent experts had inexplicably been rejected.
 The two experts should determine whether forensic science can verify  what the police verified and whether the (police) forensic expert, when  looking at the hook and the knife, applied the cautious protocols  established for this analysis and if they can identify contamination.
 For the knife, they seem already to have reached a conclusion. After  taking samples from different points of the blade, they found an  insufficient quantity of biological material. Insufficient to obtain  genetic profiles for testing. Then how could they get the DNA of Amanda  and Meredith?
 The prosecutor Giuliano Mignini is quick to point out: “We knew that  very little material was available and that the lab test done by the  police was unique because it used up all there was.”
 Then why did the court order new tests? In reality, the two experts  rejected the work of the police, saying “on that knife there was never  enough to get biological material to get DNA profiles.”
 This is the truth that emerges from the sensational and shocking new report.
 
The bra clasp: The only bit of evidence said to link Raffaele Sollecito to the crime is too rusty to test. 
  Chain of errors. 
And the discovery made on the second finding is even more  astonishing. When the experts received the bra clasp of Meredith, they  found it covered with rust. “Could not be tested,” they ruled.
 But where and how it was this important piece of evidence preserved?  How is it possible that nobody thought to keep it sealed in a vacuum  bag? The history of this clasp after Raffaele Sollecito’s three and a  half years in prison really is unique. On the afternoon of November 2,  2007, it was found under the body of Meredith by medical examiner Luca
 All of a sudden, someone remembered the hook. They rushed to recover  in a house that had, in the meantime,  undergone two searches. They  found it and, surprise, there was the DNA of Raffaele.
 Now there’s just rust.
http://blog.seattlepi.com/dempsey/2011/04/03/new-revelations-no-evidence-against-amanda-knox-and-raffaele-sollecito/