It seems that the Supreme Council for the Islamic Revolution in Iraq will no longer be claiming to take guidance from Ali Khameini, Supreme Leader of Iran, and instead follow the lead of Ali Sistani of Iraq. Juan Cole has analysis and I’ll defer to him on the ins-and-outs of intra-Shiite politics.
More structurally, I think you’re seeing here simply that it’s hard to exert control trans-nationally. When Iraqi Shiites are politically weak, such Iraqi Shiite organizations that exist are heavily dependent on Iranian support and thus prone to doing things like recognizing the lead to accept spiritual guidance from Iran’s cleric-politicians. As they gain more of a power base in Iraq, it’s natural for these same Iraqi Shiite leaders to start discovering Iraqi nationalism. That Sistani does not, in practice, seem to be all that interested in directing day-to-day Iraqi politics has to make him an especially desirable “spiritual leader” for the SCIRI leadership.