The key takeaway from the IG report is its call for the Attorney General to name a special prosecutor to continue investigating the reasons behind the U.S. attorney firings.
The reason? A lack of cooperation from witnesses outside the Justice Department:
[T]here are gaps in our investigation because of the refusal of certain key witnesses to be interviewed by us, including former White House officials Karl Rove, Harriet Miers, and William Kelley, former Department of Justice White House Liaison Monica Goodling, Senator Pete Domenici, and his Chief of Staff. In addition, the White House would not provide us internal documents related to the removals of the U.S.Attorneys.
So the stonewalling continues, including from the White House, and has succeeded in thwarting not only Congress but the DOJ Inspector General (and the Office of Professional Responsibility, which conducted its investigation jointly with the IG).
What specifically should a special prosecutor look at? Possible obstruction of justice and perjury:
We recommend that a counsel specially appointed by the Attorney General assess the facts we have uncovered, work with us to conduct further investigation, and ultimately determine whether the evidence demonstrates that any criminal offense was committed with regard to the removal of Iglesias or any other U.S. Attorney, or the testimony of any witness related to the U.S. Attorney removals.
More here.