The Center for the Study of the Public Domain has released their annual Public Domain Day reminder about artistic works that could have entered the public domain on January 1, 2012. "Under the law that existed until 1978 . . . Works from 1955." That would have included such sf works as...
J.R.R. Tolkien’s The Return of the King, which would have made the entire Lord of Rings trilogy part of our common world heritage rather than the private property of the Tolkien estate.
Fredric Brown's sf comedy classic, Martians, Go Home.
Jack Finney's classic of Cold War paranoia, The Body Snatchers, which introduced the term "pod people" into the popular lexicon.
Leigh Brackett's post-holocaust classic, The Long Tomorrow.
Philip K. Dick's The Solar Lottery.
And Isaac Asimov's time travel novel, The End of Eternity, could along with his Foundation trilogy have entered the public domain.
Luckily there are some loopholes in the current restrictive laws. While stories like Robert Sheckley's humorous "The Lifeboat Mutiny" (1955) is not in the public domain, the X Minus One radio adaptation of it is. So until the law is repaired we can at least freely enjoy it in that form.
The Lifeboat Mutiny