IMO, the worst result of a cover-up is that the terrorists will up the ante next time, to make sure their intentions and message are obvious.
You make an excellent point laz. They WANT the attention - that's why they finally did 9/11 - attacks against the military weren't enough.
At this point the leaders of AQ are probably focusing attention on Iraq and how to achieve control over it after the US leaves - per the letter intercepted. But that doesn't mean that the cells in the US are not plotting future attacks. I think the cell in Norman will be even more active considering what kind of response this latest episode has gotten. I mean - they didn't even interrogate these people.
A little Off-Topic:
Another thing that strikes me as somewhat unbelievable is because you KNOW if it were drugs and not explosives found the DEA would be ALL over EVERYONE even remotely associated with Hinrichs - charging or attempting to charge them with all kinds of conspiracy charges in order to get people to talk.
Maybe some of the DEA Agents should be transferred to fighting terrorism!!! IMHO they are better trained than these FBI guys, they've got the tools to protect themselves against these terrorists, and they could use their expertise in undercover ops and such to bust these cells wide open... THAT would be a better use of our tax dollars at this point, IMHO.