With more recent release when they release the special edition/unrated and barebones versions of DVDs, the special edition will be the default blu-ray release (Watchmen, Tropic Thunder, Iron Man, the Hangover, the Dark Knight, Inglorious Basterds, Indiana Jones and the Kingdom of the Crystal Skull).
When blu-ray first came out, early releases of catalog titles were the barebones version, but nowadays you have the studios releasing HD versions of their special editions/unrated versions (Batman Begins, Transformers, V for Vendetta, Halloween).