Author of the Pulitzer Prize-winning book "Guns, Germs and Steel" (and he's also coincidentally my cousin), Jared has an essay here on the failures of group decision making:

] . . . a sequence of four somewhat fuzzily
] delineated categories. First of all, a group may fail to
] anticipate a problem before the problem actually arrives.
] Secondly, when the problem arrives, the group may fail to
] perceive the problem. Then, after they perceive the
] problem, they may fail even to try to solve the problem.
] Finally, they may try to solve it but may fail in their
] attempts to do so. While all this talking about reasons
] for failure and collapses of society may seem
] pessimistic, the flip side is optimistic: namely,
] successful decision-making. Perhaps if we understand the
] reasons why groups make bad decisions, we can use that
] knowledge as a check list to help groups make good
] decisions.

This essay also made Slashdot today. That discussion is here:
 http://science.slashdot.org/science/03/04/28/1415211.shtml?tid=134