Personally, I think that, for the time being, yes, the terrorists are unable to cause further major damage.
I think that, had they been able to, they would have already. Put it this way- had Sept. 11 not occurred, this whole Anthrax thing would be page 3 stuff. We’ve had worse flu outbreaks.
But because it happened so soon after Sept. 11, there are some places in near-panic and people who have nothing to fear are now avoiding shopping, staying away from large events and afraid of their mail.
Add in something simple- relatively speaking- like contaminating a small city’s reservoir, and panic would explode. People would be thinking A) We’re still ‘under attack’ and B) there are still terrorists out loose in our midst. Such a thing would severely undercut the fragile state of hysteria we now have, and things would get geometrically worse.
However, such a thing hasn’t happened- and I hope it doesn’t, definitely- so there’s one of two possibilities:
A) The remaining terrorists- if any- are holing up since they know every man, woman and child in the US is looking at middle eastern folk with a magnifying glass, plus they haven’t been able to receive either orders or funding from their controllers (who are almost certainly currently hiding in a cave hoping the next laser-guided 2,000-pounder doesn’t sel the exits) and thus are all but neutralized for the time being.
Or B) There aren’t any terrorists left, considering the ones that died in the crashes and those that have been arrested or detained since then.
So for the time being, I doubt we have anything more to worry about, save for locating bin-Laden and turning him over to the Saudis for a ritual beheading.