Biological weapons have a serious drawback: they consist of entities that reproduce themselves. That means that they can get out of control and infect everyone, not just those they are aimed at. This is the reason that bioweaponeers look for diseases most of us find exotic: they want bacteria that will infect the targets but not spread so easily that they are a danger to those using them.
The big news of the past few weeks has been that Dutch and American researchers, Ron Fouchier and Yoshi Kawaoke, and their teams have made new influenza viruses that kill most of the organisms they infect and are easily spread through the air. The National Science Advisory Board for Biosecurity (NSABB) has advised the journals (Nature and Science) to which the papers describing the preparation of these viruses have been submitted to publish the papers with key passages relating to the preparation of the viruses deleted. The purpose, of course, is to keep the critical information of exactly what the operative mutations are and how to induce them out of the hands of amateurs and terrorists.
Because of their communicability, these viruses present much greater danger than the anthrax attacks of 2001. If an amateur tried the prep and messed up, infected his family, things could get ugly. We have the previous example of SARS that shows that something like this could be contained, but people would die.
On the other hand, if researchers know the components that make these viruses so virulent, they may be able to come up with defenses against them, maybe even a vaccine against all varieties of influenza.
I feel strongly that the NSABB has made the right call. Some people feel that information wants to be free, or something like that, a libertarianism of the intellect. Consequences be damned, I guess. And that link has it wrong: specifics of the mutations and how they are induced make it much easier to produce the viruses. Knowing that such a thing is possible is useful to those who would reproduce the process, as is any additional information in the papers. But it's some distance to figuring out the exact steps in the laboratory.
The people who discovered fission in the 1930s and realized its implications faced the same sort of dilemma. Here's a historian who discusses how that worked.
It's impossible to keep this sort of information secret forever. I'd be happy if we could damp down idiotic attempts to do it in someone's garage until we have some idea of how to make a vaccine.