From the Good Blog:

Where Did the Money to Rebuild Iraq Go?

From the Special Inspector General for Iraq Reconstruction, July 27, 2010 (PDF):

Weaknesses in DoD's financial and management controls left it unable to properly account for $8.7 billion of the $9.1 billion in DFI funds it received for reconstruction activities in Iraq. This situation occurred because most DoD organizations receiving DFI funds did not establish the required Department of the Treasury accounts and no DoD organization was designated as the executive agent for managing the use of DFI funds. The breakdown in controls left the funds vulnerable to inappropriate uses and undetected loss.