im sure it CAN be, the question is WILL it be...we already have different categories based solely on resolution (wallpapers,artbooks, and others) but i can see what you are saying.
some images do have a tag "widescreen" for 1920x1200 and the like, although not all widescreen images have the tag and the "regular" images have no tag.
try cyclone, this program will automatically finds images on this site that fit your screen and changes them every so often.