What might be useful is a script that could be user-adapted to a variety of different circumstances. It could offer the option to specify the image to save (same filename, specific name or all images) to each of the image containers (imagelist, screenshots, froncover and cdcover). Froncover and cdcover only take one image, so I'm assuming "all images" would result in only the first image found being saved. Just to be clear: I'm thinking of nothing more than a well-documented script that most users would be able to edit to make these choices.
One might configure this script to save "same filename" as a poster, "front" as froncover, "back" as cdcover and "all images" as screenshots. It would be nice if "all images" excluded images saved elsewhere (i.e., it's "everything else"). And I'm assuming all image types can be handled without being user-specified. I particularly like the idea of dumping all images into screenshots. That provides a way to see them all in PVD—so individual images could be saved and reloaded elsewhere (e.g., the "extra" images might be alternate posters). And if they're not needed, they're easily deleted with the Remove all screenshots command.