Looking at the EXIF data on wiki.... it was shot at 105mm... Is that a 24-105 F4? I would have thought's they'd use a 70-200f4 or 135 F2. Maybe they have and it is pure coincidence that the focul value ended up being exactly 105mm
Why wouldn't you want to use a 24-105 f4 to work with Obama? It's quite a good focal length to carry around. It has to be remembered that he gets to shoot in rooms, corridors, lifts as well as in hall and so on.
the fact that he is working with a 5D2 is a fair sign he needs to travel light, so 5D2 and 24-105 is fairly light, as opposed to a 1Ds3. Probably carries two of them, 1 with 24-105 and 1 with 70-200 permanently fitted - without reading all the story. And for good measure, a couple of 430EXII flashes. These with a supply of CF cards and batteries should keep him going all day.
The real question is, how many 5D2's has he gone through in the course of this contract?