Which one do you mean? The sorting thing? This was described in this thread before (see the big blue sketch).
And the scribus darktable interaction? What I mean is that an image could be linked between scribus and darktable, such that a change in darktable will update the image in scribus and that you have the possibility in scribus to e.g. right click and select a context menu entry to get back into darkroom of darktable with the image opened. An explicit export would not be required in that case, but an UI for linking the image in dt and scribus would be necessary.
One important aspect (this feature idea I already described somewhere else here on pixls.us) would be that the crop in darktable is only used for an initial crop in scribus and that the image parts cropped away are available if necessary, e.g. to fill page bleed etc. A change of crop in scribus should not be reflected back to darktable, since in darktable it is an artist’s decision which crop is selected and in scribus it is the designer’s need to deviate from the artist’s decision 
.
Edit: Found the discussion I referred to before: Feature request/idea that concerns several programs/projects: Crop info in metadata instead of cropped image - #36 by Jonas_Wagner. If you make it to read half of the thread, please continue to the end, there are some positive turns in the second half 
.