Interesting.
Al Qaeda has implemented efforts to end the schism between Sunni and Shiite, instead preferring to concentrate on the west as its main enemy. In fact, I understand that even discussing differences between the sects is considered a sin under AQ's twisted interpretation of the Koran.
Of course, thetical differences have bever stayed AQ's hand in alliances past.
Here is a presentation of the world according to bin Laden and al Qaeda by Brian Jenkins at RAND
http://www.oss.net/dynamaster/file_archive/040509/8e4fee5357af4b569ce5e2f4bdcedf5f/Brian%20Jenkins%20on%20Al%20Qaeda%20Code%20and%20Direction.ppt