Pete Souza - White House Photo / via AP

A detail crop of Clinton from the Situation Room picture.

Update, May 5, 10:09 a.m.

The Secretary of State made some comments in Rome today calling the common interpretation of her expression in this picture into question. From the NBC News HOT file:

THESE REMARKS WERE MADE IN ROME THIS MORNING ABOUT THE PHOTO SNAPPED WHILE WATCHING THE OPERATION TO TAKE DOWN BIN LADEN IN THE SITUATION ROOM...THE QUESTION ASKED WAS WHAT WAS SHE THINKING AT THE TIME:

06:20:55 --Now with respect to your second question, those were 38 of the most intense minutes. I have no idea what any of us were looking at at that particular millisecond when the picture was taken. I'm somewhat sheepishly concerned that it was my preventing one of my early spring allergic coughs, so it may have no great meaning whatsoever. 06:21:18

Film at 11. . . Here's the video:

She also addressed much weightier issues. Read more: Clinton on terror: 'It does not end with one death'

Original post:

Pete Souza / The White House

President Barack Obama and Vice President Joe Biden, along with with members of the national security team, receive an update on the mission against Osama bin Laden in the Situation Room of the White House, May 1. Please note: a classified document seen in this photograph has been obscured.

This image is history in real time.

As the AP reported:

WASHINGTON — From halfway around the world, President Barack Obama and his national security team monitored the strike on Osama bin Laden's compound in real time, watching and listening to the firefight that killed the terrorist leader.

Gathered in the White House Situation Room, members of the group held their breath and barely spoke as they waited to see whether a carefully crafted yet extremely risky plan would succeed, said White House counterterrorism adviser John Brennan. Obama had been playing golf but returned to the White House for the suspenseful watch Sunday.Related: How satellites helped get Osama.