Since the “Fact or Fiction” story generated so much indignation, here I’ll describe what I think could be done to negate the threat described.

For the ebola virus, I remember some article in the SF Chronicle about fish being used as bio-terror detectors for city water supplies. So I type “fish water supply terror” into Google, and sure enough, bluegill fish are being used to detect dangerous chemicals in the water supplies of San Francisco, New York, and Washington because they are better than the best artificial sensors. However, it seems they don’t respond to bacteria, or perhaps not viruses… luckily, there was recently a news item about a super-improved virus detector, that can detect a virus in seconds. I assume that we are starting to use them to observe our municipal water supplies more carefully nowadays. With more technology, maintaining security will become easier, as long as the white hats stay ahead of the black hats. As Brian Wang also mentioned in the comments, we need to improve our intelligence. Luckily, bio-terror is a high-profile terrorist risk, like conventional explosives, and most cops are probably trained on what to do in the event that an outbreak occurs - quarantining, etc.

For nuclear weapons, there are very effective uranium detectors nowadays, that can sense uranium through crates even. Thanks to post 9-11 vigilance, we can hope that an atomic bomb won’t make it into the country. For nonproliferation activities, I recommend “Preventing Nuclear Terrorism” by Matthew Bunn. Apparently the President isn’t doing enough. We need to get enriched uranium out of sensitive sites overseas with inadequate security. Also, to eliminate the cheap enrichment of uranium in the future, it might be a good idea to ban nanofactories, or at least be absolutely sure that no desktop manufacturing appliance can be used to create any device that enriches uranium, or breeds it. We need to switch over to solar, fusion, and ‘denatured’ thorium energy sources as soon as possible.

Unrelated: fascinating post by Paul Gowder from Overcoming Bias.