This little 1,000-word story has been the source of much controversy, and in ways its author never foresaw, changing a certain science fiction award forever. Copious further info on that can be found via Google. My own thoughts are that this piece, which mimics the form of a certain popular children's book, deserves all the accolades it's garnered. Swirsky addressed and answered any debates about the story's genre metafictionally in the story itself - and, yes, it most certainly is a horror story.
Read it here.
Read it here.