Originally published in the collection by the same name and in the author's magazine, Asimov's. Reprinted by George Zebrowski, Gardner R. Dozois, Sheila Williams, and Orson Scott Card--two of which were genre retrospectives. It was up for the Hugo, the Nebula, SF Chronicle awards and actually won the Locus, Asimov's Reader Poll, Seiun awards.
Like her last name indicates, without authorization Dr. Linda Rash introduces fractal geometry to the robot's positronic brain. It subsequently begins to dream. Dr. Susan Calvin isn't sure what to make of it until she interrogates the robot what it dreamed:
The robots are weary and await the one man who says "Let my people go." When the robot says that he is the man, her worst fears are confirmed.
Dreams, the story appears to say, are the source of what makes us human.
Wikipedia's additional interpretation is that "Elvex is destroyed not for the capability of human thought and mannerisms, but the unconscious desire to escape the inequality that robots were created for." That may be one reading, backed up by a Biblical allusion to Moses speaking to the Egyptians (I discuss this further in "Little Lost Robot" and "The Bicentennial Man"). The other reading is that, because no humans exist, underneath the robot conscious layer is the subconscious desire to wipe out the human race.
It seems probable that the award attention was the readers' ways of saying they wanted more of this terrain.