Stratfor has an analysis (Iraq: Next Moves for the Shia) that suggests coordination between Iraq's Sunni politicians (usually the moderates) and the Sunni hardliners (who provide a human buffer zone between insurgents, such as Zarqawi, and the government / Americans). That indicates that the Sunnis, overall, are tired of fighting the Iraqi government and can see that enraging the Shia will not get what they want - protected status or the chance for more power.
Previously, I would not have thought that the hardline Sunnis were getting noticibly tired of fighting the Iraqi government, but backing actions that leverages the Americans against the Shia is an excellent wedge issue and a very savvy political move. The Sunnis, overall, are more aware of politics and what political manoevers can achieve than the Shia, what with having been in power throughout Saddam's era. Further, the curious 17 raids conducted immediately after Zarqawi's death, suggest little time for actual analysis of gathered intel, and the subsequent almost 470 raids in the last few days shout out that there's been a coordinated Sunni effort to force the spotlight onto ruling ability of the Shia.
The Stratfor analyses of the intra-Shia schisms and the tensions are on target - the unknown and uncontrolled influence of Iran's definitely more to the fore with the head of the Sunni insurgent snake gone.
Whether this is a calculated move or not between the two halves of the Sunnis to force the spotlight on the Shia is almost academic - it's now in the Shia court to get themselves in order. And it's about time.