There is no getting away from the NAS report conclusions, as reported worldwide: the science does not support FBI's claims that Ivins was the anthrax perpetrator.
See articles from the AFP, NPR, AP, Science, and a later WP article.
The FBI responded that their case was based on a totality of the evidence, not just the science. But when the rest of the FBI's evidence is examined, one finds only smoke. There has been no physical evidence tying Ivins to the case. The totality of the FBI case against Ivins rests on colorful and sometimes exaggerated personal quirks and odd habits. The FBI has presented no convincing evidence that Ivins had the means, a motive, or the oppportunity to commit the letters crime. (See my Nov. 29, 2010 talk on this subject here.)