It was recently announced to the public about a month ago that the anthrax used in the 2001 attacks shortly after 9/11 was not weaponized. That determination had been made back in 2002 by researchers at Sandia National Labs, but they weren't allowed to say anything until now.
Scientific American has now published an article about the science behind the Sandia investigation.
It's been public knowledge for at least 2 years that the anthrax wasn't weaponized.
But this past Wednesday, at a Senate Judiciary Committee hearing, Sen. Arlen Specter asked FBI Director Robert Mueller, "Was the anthrax weaponized, that is, engineered to make it more deadly or not?"
I'd suggest Specter's staff read the Scientific American article or the Sandia press release cited here for the answer. There is no longer any mystery.