A New Sith
Okay, so I lied when I said I was going to bed. Josh just pointed to A New Sith, or, Revenge of the Hope, an excellent Secret History-style exegesis of what's really going on in the original Star Wars, in light of what we learned in Revenge of the Sith. (Note: it contains spoilers for all six movies.)
It's not precisely what was meant by the original use of the term "retcon" ("retroactive continuity"), but I think it fits under the term's wider definition. Nice work, Keith Martin.
Oh, and that reminds me to point to Prequel Generation Questions A New Hope, in which we learn what a 7-year-old thinks on seeing A New Hope for the first time after seeing the prequel trilogy.