Being able to link different versions of a work (pre-prints, post-prints, author's revisions, etc) to a canonical identifier is a subject that's come up recently, both here and elsewhere. It's debatable whether all versions of a work (arXiv preprints, publisher's PDFs) should (or could) have the same DOI, for example, or whether there should be an external linking mechanism.
This seems to be the kind of thing that a Handle server (of which a DOI resolver is a special case) could provide: given an identifier it would return metadata about the original object, including, hopefully, Dublin Core fields that deal with relations between objects: isVersionOf, hasVersion, isReplacedBy, replaces, isFormatOf and hasFormat.