I thought that the color of the Obama poster worked really well with the colors of these houses. And in a way it almost looks like someone looking out of the house. It doesn't look quite like a poster... there's just a little bit of a double take needed. And I think the balance of the shot works well. I have another one at a different house that has a more of green/grey feel to it, matching the opposite side of the poster.
What I liked about this image was that I see a connection between the houses which seem middle class or even poor, and the image of Barack Obama. On another note, the poster says "HOPE", yet the photo has a very somber kind of feel to it. It's not sunny, and in fact, it almost looks like it's about to rain.
However, that is entirely imagined! These are actually very expensive town homes right off of South Street in Philadelphia, and, it was a sunny day.