This should be taken with a grain of salt; the tale is horrific, and hopefully simply a negative propaganda campaign. But...
If it is true, then war crimes far beyond those of the prison scandals or use of banned WMDs like napalm are being committed - atrocities which should merit death for the ones responsible. Including the highest ranks of the responsible government.
Saudi Government Daily Accuses U.S. Army of Harvesting Organs of Iraqis
December 24, 2004 No.834
In the Saudi government daily Al-Watan, a n article from Brussels written by Fakhriya Ahmad charges that, based on alleged secret European military reports, the U.S. military in Iraq is harvesting and selling human organs. The following day, the story was also published in the Iranian daily Jomhouri-ye Islami,  as well as the Syrian daily Teshreen.  The following are excerpts from the article: 
"Secret European military intelligence reports indicate the transformation of the American humanitarian mission in Iraq into a profitable trade in the American markets through the practice of American physicians extracting human organs from the dead and wounded, before they are put to death, for sale to medical centers in America. A secret team of American physicians follow the troops during their attacks on Iraqi armed men to ensure quick [medical] operations for extracting some organs and transferring them to private operations rooms before they are transferred to America for sale.
"The reports have indicated that a number of those killed in 'Abu Ghraib' and other prisons were subjected to operations for extracting their organs. Following their mutilations, the bodies were discarded far from the prisons to conceal the facts. The reports revealed that that the American forces restricted the media by force to prevent them from getting near the scenes and recording the events. But the relatives of the Iraqis are aware of these facts. The reports have [also] indicated that the military forces of the European allies have noticed the absence of organs from the cadavers that were dealt with by the Americans and have reported to their high command, which instructed them to maintain silence and to avoid the discussion of the subject due to its gravity, while the military and intelligence high command have written secret reports about was observed by their forces and sent them to the European ministries of defense for their information."
As I mentioned, it's a horrific story. It has the initial flavor, to me, of being propaganda. However, such stories of brutal medical experiments by the Nazis in WWII would likely have the same 'flavor' until either substantiated or disproven...so, let's hope these stories are not true.
If they ~are~ true, then we too are guilty of crimes against humanity if we fail to put an immediate stop to such practices.