I was unaware this book was out of print. A new, revised edition was released in 1989, which included extensive footnotes by Le Guin, including an interesting redux of her essay, "Is Gender Necessary?" regarding the feminist content of her most famous novel, "The Left Hand of Darkness."
In whatever version, "The Language of the Night" is, quite simply, essential reading for any devotee of science fiction and fantasy literature. Among the standout pieces are "The Child and the Shadow" and "Myth and Archetype in Science Fiction," both of which use Jungian psychological ideas to get at the root of fantasy's imaginative power. Also compelling are "Science Fiction and Mrs. Brown," in which (by way of Virginia Woolf's essay "Mr. Bennett and Mrs. Brown") Le Guin examines whether science fiction literature can really do justice to human character, and the hilarious "From Elfland to Poughkeepsie," a delightful critique of tone-deaf fantasy authors.
All in all, an excellent read.