Sounds like the secular Sunnis (Saddam's old base) have taken enough shit from the religious Sunnis, who aren't even Iraqis.
If al Qaeda in Iraq is smart, they'll try to figure out where they lost their allies. And start building some bridges. Maybe some heads will have to roll first - - the ones who caused this potentially disastrous split in the first place. They need to keep their focus: the enemy is still Amerikkka and only Amerikkka can profit from the schism.
Ultimately, the responsibility lies with the leadership of both factions. If they can't bridge their differences and present a united front to the occupation forces and their collaborators, then they deserve to be subjugated by infidels as the Arabs always have been in the past. The Vietnamese bridged their differences and put up a united front (the NLF) against the foreigners. God helps those who help themselves.