Obama's is incredibly effective at conveying his story. Its value donned on me when my roommate quickly sketched it on our whiteboard on our door. Any one who saw the drawing immediately recognized the red, white and blue stripes and sunrise. Needless to say, my roommate is no graphic artist but the crude drawing on our door was unmistakable. The ability to easily recreate a logo while retaining its message consecrates its effectivness.
Here is a two part interview with Sol Sender (who names their kid that?), a creative director at VSA Partners, describing the development of the Hope Logo.