I saw the story on another site, they had a picture of the GI Joe doll, with all the plastic guns and little cammos, right next to the pic of the would-be captive GI. It´s a doll, no question about it. Any doubts anyone would have would dissipate upon glancing the size and shape of the M-4 held pointing at him/it. I´m surprised anyone would even consider this being an actual photo...
But this is nothing new. There have been crude hoaxes like that on the net ever since the war started. Remember that american guy who faked his own beheading and posted it on the net?
Well, at least we got a good laugh out of it...

EDIT: Here´s the link for the story.
http://www.msnbc.msn.com/id/6894934/