Well he is Saudi and from what I understand Saudis and Iranians do not particularly care for each other. I'm sure there are remote areas where a man like Bin Laden would be welcomed and harbored though.
Perhaps the CIA has known this for some time. I know there have been rumblings about Bin Laden being in Iran for a few years now, I'm not sure how likely it is but it is possible.
Bin Laden is actually a Yemeni but the family fortune came mostly from business done with the oil rich Saudis.
The basic split between the Shiites and the Sunnis came with the death of the illiterate, treacherous, blood thirsty, greedy, false prophet Muhammed.
The Shiites wanted a direct descendent of Muhammed to be the next caliph, the Sunnis wanted to elect caliphs.
That is the basic difference, all other major tenets are identical.
The Sunni Prime Minister of Turkey has said he has no problem with a shiite caliph with worldwide authority.
Bin Laden may be a direct descendent of Muhammed, his original homeland in Yemen is dominated by a tribe that does claim to trace it's linage all the way back to the lecherous Muhammed, so for bin Laden or some close associate could be named the islamic caliph so as to unite islam completely.
Whether bin Laden is actually in Iran or not, we do know that Iran has sent Republican Guard forces into Iraq to do war against us and to arm other groups with enhansed IEDs etc, and has harbored Taliban forces who are fighting in Afghanistan.