Developing...

From the Marine Corps Times:
“Apparently, the worst is yet to come,” Sen. Lindsey Graham, R-S.C., an Air Force Reserve colonel and military lawyer, told reporters outside the Senate committee hearing room. “We’re talking about rape and murder.”
Graham was referring to video images of alleged abuse of detainees inside the prison. Rumsfeld has acknowledged that such footage exists.

Update: I've come across some more information (thanks to atrios) on the unreleased videos and imagines and it sounds very bad indeed:
“There are other photos that depict incidents of physical violence towards prisoners, acts that can only be described as blatantly sadistic, cruel and inhumane," [Rumsfeld] said. “... It’s going to get a good deal more terrible, I’m afraid.”

Rumsfeld did not describe the photos, but U.S. military officials told NBC News that the unreleased images showed U.S. soldiers severely beating an Iraqi prisoner nearly to death, having sex with a female Iraqi female prisoner and “acting inappropriately with a dead body.” The officials said there was also a videotape, apparently shot by U.S. personnel, showing Iraqi guards raping young boys.

Graham is right, the worst is yet to come.