Link Relations for Simple Version Navigation (draft-brown-versioning-link-relations) has just been updated; it defines Atom link relations for navigation between a resource and its versions. since i missed the first version, i have now added it to the Atom Landscape Overview as a new draft regarding Atom extensions.
in theory, this draft can be regarded as a standalone proposal to add some more possible link relationships to Atom. in practice, it seems that the draft mainly targets Atom applications in WebDAV and JCR environments. a final version of that draft should also add the newly defined link relationships to the proposed IANA registry for link relationships, but since this one is also still under development, it remains to be seenwhich one is moving along faster.