That I buy - to a limited degree. I haven't seen tons of evidence - but I would imagine it was all under the guise of "The Enemy of my Enemy is my Friend".
However, there is no question that TODAY al Qaeda is involved in Iraq. But under an authoritorian secular regime, I don't think al Qaeda was entirely welcome. Especially since it was calling for the overthrow of governments like Saddam's.
Not entirely welcome I agree, but for UBL to use Saddam they didn't need to be snuggle buggle bedtime buddies, and vice versa. Lest we forget that Saddam harbored other uber-terrorists like Abu Abbas, Abu Nidal, Carlos the Jackal, and all agree his regime knew Zarqawi was in N Iraq (all agree because Saddam had his intel people in the same terrorist camp).
Also, don't be lured into thinking that Saddam was all secular etc. After 91 he wasn't the same. Further, if the idea that UBL would work with the US to fight the Afghans is acceptable to many, then why wouldn't UBL work with a Muslim to attack the Great Satan?
Try this
http://www.mediaresearch.org/rm/cyber/2004/binladen061704/segment1.ram