Bob Owens of Confederate Yankee has a some new information up on Pajamas Media. It looks like the leak did come from someone in the Army:
These documents, which I sought via a Freedom of Information Act (FOIA) request, were apparently leaked at a high level, and the information contained in the documents is unredacted. They have been verified as being accurate by military sources, and the source of the leak is said to be under military investigation.
This passage stands out as well:
For all of his faults, including writing three stories published in The New Republic that contained inaccurate, un-fact-checked, or blatantly false information, sources who have recently interviewed the soldiers in his unit indicate that Beauchamp is attempting to atone to his fellow soldiers and reearn their respect. He has, as much as I think he can without setting himself up to be sued for fraud by TNR, done as much as he can to rectify the wrongs he’s committed. His fellow soldiers and commanders are willing to give him a second chance. Perhaps we should, as well.