9/11 Photo - What does it show?

I saw this link on Facebook, and have to admit, it is to a photo I have never seen before, in spite of being well known, clearly.

There seems to have been a lot of fuss about it, although as thousands of people witnessed this event at first hand, and millions more on the TV, would it not be possible for something akin to a relaxing moment to be captured digitally. I doubt that any who were eye witnesses went about all their business normally that day, most would be deeply affected. But we do still compartmentalise our feelings and deal with trauma (or ignore it) by carrying on with our lives. 

Incidentally, one of the people in the photo thinks he was misrepresented in the photo and I think that is probably the case.

See what you think, and what does it say about the power of photography?

http://apps.facebook.com/theguardian/commentisfree/2011/sep/02/911-photo-thomas-hoepker-meaning?fb_ref=U-LpO30L8FDSCo45DtI9Z4lW-CFCONX01FRS-3xj66XXX&fb_source=home_multiline&fb_action_types=news.reads