Craig Venter says fears about abuse of the capability to create synthetic life forms (reportedly advancing with the publication today of a paper about the construction of the DNA code of a common bacterium) are largely irrational and unfounded. (See, for example, his intervention in Life: What a Concept: "it's a very low threat that people like to use to scare people, but it's not a real one" [p. 32]).
But others do not share his optimism, especially when it comes to viruses (in 2001 Australian scientsts gave everyone a nasty surprise, and a synthetic virus was created in 2002). Martin Rees bets there will a million casualties from bioterror or bioerror between 2002 and 2020. And it's reported that Mike McConnell, the director of U.S. National Intelligence, thinks "there could be a time in the not distant future when teenagers can design biological components just as they do computer viruses today".