The fundamental flaw of the Iraq Study Group is the assumption that there is still some sort of a national nucleus that can be called 'Iraq'. It's absolutely not true.
The 'government' cannot protect the people. The 'government' has no authority outside the Green Zone. The Kurds are de-facto independent. Warlords such as al-Sadr are running rampant through the countryside, while smaller groups, outside anyone's control other than their own, are gleefully practising ethnic cleansing (or should we bump this up to genocide, now?). Recent reports say that the violence is 100 times what's being reported in our press. Millions of Iraqis have fled the country, typically the more educated or wealthiest.
And for all those willfully blind people who insist there's still a there, there, they will never be convinced that there's no putting the pieces back together... not when our last troops are out, sometime in the next administration; not when the civil war finally dies down sometime around 2018; not when the violence spreads throughout the Middle East and we find ourselves with fresh Iraqs in Afghanistan, Lebanon, and Saudi Arabia.
All we can do at this point is get the frack out, NOW, and let the nightmare we've created burn itself out.