The photo of the American hostage is being shown on Sky News.
Link here:
http://www.sky.com/skynews/article/0,,30000-1130980,00.html
According to the story, the man gave his name as Thomas Hamill. Given his age, my guess is that he's a civilian contractor, not a soldier. Time to hit google.
The American press won't disclose this information, but the information is available to anyone with an internet connection on the Sky News website