1. A computer-implemented method, comprising: at a portable electronic device with a touch screen display, displaying an array of thumbnail images corresponding to a set of photographic images; replacing the displayed array of thumbnail images with a user-selected photographic image upon detecting a user contact with a corresponding thumbnail image in the array, wherein the user-selected photographic image is displayed at a larger scale than the corresponding thumbnail image; and displaying a different photographic image in replacement of the user-selected photographic image, wherein the different photographic image is selected in accordance with a scrolling gesture comprising a substantially horizontal movement of a user contact with the touch screen display.