I see you did your own research after this post, and came up with some pretty good answers.
The bottom line is that the upper echelons of the Saudi royal family are pretty good allies, when they can be. They have a very tenuous grip on power which is threatened not only by a declining economy (national income -- GDP -- is not growing nearly as fast as the population) but by radical Islamic elements and less favored members in the wings of the royal family itself. If they are perceived as getting too close to us without getting anything in return, they think they'll be dethroned, and they're probably right.
One glimmer of good news in all this is that it might cause OPEC to implode with each member increasing production. Saudi Arabia will probably benefit more from such a development than any other ME country, and will benefit even more if we embargo oil shipments by a couple of the other ME producers.
What can we give them in exchange for the right to use their bases to attack bin Laden, and probably other Arab countries?
A current post says that the allies called off a first attack because of cold feet by Saudi Arabia (and 2 others). Rumsfield is personally going over there to investigate. That means it's serious.
bin Laden has said that one of his principal goals is to destabilize friendly Arab regimes. If he forces a revelation of the extent of his support in Saudi Arabia it will force a crisis.
Or at least that's my current understanding.