Seriously, this is very humorous, but every organization has this potential weakness. In al Qaeda's case, they are ripe for defeat if we can infiltrate them...and corporatize them. In the extended section of the text, I will explain why al Qaeda will have to take on a more corporate-like structure, and how this will ultimately destroy them. The sooner they are forced into this path, the sooner they will no longer be a threat. In fact, I'd say that judging by their actions in the past, they are already on the way.
Finances
It's clear that many nations have frozen al Qaeda assets and shut down charities that give them money. As a result, al Qaeda's budget has been shrinking, which means they have less money to spend on an attack. Therefore, it is vital that they implement a budget review board that can prioritize their terrorist activities, and only sign off on the ones that reflect their core terrorist activities and beliefs.
Project Management
It's also clear that there is a lot of disorganization within the terrorist group, therefore they need new project managers. Even 9/11 was supposedly a scaled back version of Project Bojinka, so if they really wanted to pull something off in a methodical way, they have to start planning better. This will require a change control board, as well as a project management team made up of people who can make a timeline for the project, assign tasks and action items to specific individuals, write documentation, and provide overall direction for their plots.
Human Resources
Right now, al Qaeda recruits people through various means that I don't really know about. What they need is a presence that can help them pick out the people most suited for their cause, and to provide them with the middle management that they will need to plan and manage everything that the organization will require. Plus, they will have to work with outside recruiters and make sure that nobody is excluded due to their religion or gender.
Outsourcing
Unfortunately, the new levels of planning and organization that al Qaeda would have taken advantage of would probably cause further budget problems. In order for them to continue menacing the U.S., they would have to lay off their lower level jihadists and outsource the terrorism to cheaper nations. India would be convenient, due to their proximity to Pakistan. The unfortunate reality for them, though, is that outsourcing does not work as good, so the most they will be able to expect is for the outsourced terrorists to leave flaming bags of poo on the front steps of the infidels, or maybe to set off a firecracker in their mailboxes.
The results
If al Qaeda were to corporatize themselves or adopt Western business practices, then they would be incapable of attacking the U.S., but would still think that they are accomplishing something because they are all too busy running around like idiots talking about source control and project plans.