I assume he was sitting wherever the hell he wanted, and the whole room is his laptop.
I am positive that if the President asked to have a seat at the table, someone would move. (Biden and Clinton direct their stares at Gates, who moves. 
)
What I eventually concluded was that the President came in last. The seats at the table had already been taken (I see Biden, Webb, Clinton, Gates), and Obama might have said “No no, stay where you are. I’ll take this one.”
But my first impulse (of the scene with Biden/Clinton/Gates) was to question why they would need lap top access, but the Prez does not.
I don’t think anyone there needs the laptop except Webb. I imagine he and the others seated were monitoring the operation for some time. Obama came in and grabbed a seat when somebody said, “Mr. President, we’re almost there.” Word got around that shit was about to go down, and the rest (those standing) crowded in to watch.
Because really Biden is the power behind the throne. Like Cheney was…
Woops! I missed naming Deputy National Security Advisor Denis McDonough as being at the table (but with no laptop). (He’s the dude between Webb and Clinton.)
If you read the Dope, please accept my apologies.
FYI, all of the faces in the photo have names attached to them in this web article:
http://hypervocal.com/news/2011/photos-national-security-team-in-white-house-situation-room/
Edit: Sorry. I see this has been covered in post #11. :smack:
Which explains why The Chairman of The Joint Chiefs of Staff and The White House Chief of Staff are standing.
Was anyone sitting on the other side of the room? Was the photographer just lucky that all the famous people decided to stand or sit on one side of the room?
They all appear to be looking at a screen.
Except General Webb.