According to the e-rumor fact-checking website, Truth or Fiction, this touching story is the truth.  Check it out - it’s good to remember that, along with all the mayhem and madness going on in Iraq & Afghanistan, there’s quite a bit of this happening too.  Here’s what the site says:

Summary of the e-Rumor:  

A picture is attached to this e-Rumor.  It is that of an American soldier holding and comforting a small girl who is resting in his arms.  The email says the soldier is John Gebhardt and the little girl was the victim of insurgents who shot her in the head and executed her family.  It is said that she cries and moans and that John seems to be the only one who can calm her down.  

The Truth:  
According to an article in Air Force Print News in November, 2006, the story is true.

Chief Master Sgt. John Gebhardt, was superintendent of the 22nd Wing Medical Group out of McConnell Air Force Base in Kansas.

The picture was taken in October, 2006, while he was deployed to Balad Air Base in Iraq.

The young girl had been shot in the head and had extensive injuries.  The insurgents who shot her killed both of her parents and many of her siblings, according to the article.
John Gebhardt's wife, Mindy, said that this little girl's entire family was executed. The insurgents intended to execute the little girl also, and shot her in the head, but they failed to kill her.
She was cared for in John's hospital and was healing up, but continued to cry and moan. The nurses said John was the only one who could calm her down, so at the time of the picture taking, he had spent the last four nights holding her while they both slept in that chair. The girl was coming along with her healing.

Sweet.  And contrary to ancient stereotypes, this here is the essence of sex appeal, boys!