I have to admit I first relished this post for the snarky comments in the comments section, but it is asking a real question: what do (the designs of) these images say? There are some savvy responses, including:
Looking at these from a perspective as a documentary film maker, these two pictures fall into two very different photo/film traditions. Obama and Biden are staring off into a vista that the viewer [can't] turn to see hemselves; the idea is to project a shared journey into some presumably hopeful future. The folks in the photo and the folks looking at the photo are supposed to be doing something together; the viewer is with Obama and Biden.
The McCain/Palin image, of course is staring right out at the viewer: the two figures are trying to do something to the viewer more than with him or her: to persuade. It's more immediate than the Obama campaign's approach, which has power. But it is a pure pitch, and as such it runs the risk of falling into the trap of seeming more like a pitch for a product than an introduction to two very important people.
In short, it's very much a Judith Williamson semiotics-of-advertising exercise, one that reveals how important connotation can be to image meaning - yet subjective to the point where the above example is a Rorschach test - and invites us to think of formal determinism of the signified. (At least that deterministic assumption is built into the advertising and design professions.)
I've often considered spending some time in my intro class to read still visual images before hopping into the realm of interpreting moving images and film narratives. The idea of getting students to read a movie poster or ad seems an appealing one.
FROM THE COMMENTS: Girish directs me to another ad image close reading, by Tucker Teague, and "zunguzungu" brings up an interesting piece by Roger Ebert on still-image movie analysis. Ebert's reading does not strike me as semiotic; instead, he's one part formalism, one part Christopher Alexander-ish belief in visual rules. Though I could see how these distinctions would seem pedantic to some.