So someone falsely told Harlan Ellison that K. Tempest Bradford was saying Mean Things about him. Instead of saying, "hey, don't be mean," or even "you are a mean person for saying mean things," he goes straight to the racist slurs, calling her an "NWA," a "swineherd," and a woman of "Cuhluh" (which is apparently some horrible attempt at "ghetto" phonetics, rather than a Lovecraft reference). Also says he wants to hit her, for extra classiness, and pulls out his token black friend "discovery" Octavia Butler. (Various comments and dissections of this at Tempest's blog.)
Then he issued what he told other people would be an apology, which is . . . not. That's quoted in full at Tempest's blog; I recommend 
yeloson's summary of its full non-apology-ness.
Do not say: oh, it's just Harlan, he's like that: being a jerk doesn't get you a pass on racist comments. (Indeed, if it did, it would be quite the perverse disincentive.) Do not say: oh, it's just Harlan, no-one cares about him anyway: he's still looked up to by many as a major figure in the field, and anyway, I'm not allowed to call out racism by random people? Do not say: oh, it's just Harlan, he's really a nice guy in real life: this is real life.
Look, he called someone a n****r as an insult. You don't get to do that. And it's important that we say, no, you don't get to do that.
References: Ellison's webboard doesn't do permalinks; his first post is timestamped "Thursday, July 23 2009 19:27:11" and is currently on the second page, but will eventually scroll further back. His second is timestamped "Friday, July 24 2009 16:35:36" and is still on the front page.