Enclosures are a kind of link (at least for Atom). Should Entry.enclosures become a property? What about the reader.enclosure_dedupe plugin that updates .enclosures? Would this be a backwards-compatible change?
Entry.link should likely be a property returning the link with rel=alternate. Is this what feedparser is doing, or is there additional logic?
What should the rel of custom link types like the ones coming from the share plugin be? Atom says rel can be any fully qualified URI. (Would reader:share/twitter work?)
We should expose Entry.links (Atom, feedparser), so it can be extended by plugins like reader._plugins.share.
Some thoughts: