Well, I had certainly never heard that, or thought of it that way. I've always just assumed that it came from both a pot and a kettle being black, and, therefore, for one to call the other black is just ridiculous when it is the same thing.
So, I turned to my old friend Google. Here's the best explanation I could find:
POT CALLING THE KETTLE BLACK - The "Morris Dictionary of Word and Phrase Origins" by William and Mary Morris has more detail about this phrase than other reference books: "There are two slightly varying interpretations of this phrase, which is used figuratively to apply to persons. One theory is that such action is ridiculous because they are both black, presumably from standing for years on a wood-burning stove or in a fireplace. (Note from ESC: iron pots and kettles are already black when new.) So the pot as well as the kettle is black (evil) and neither one is better than the other. This supports the explanation of the phrase as given in 'Brewer's Dictionary of Phrase and Fable': 'Said of one accusing another of faults similar to those committed by himself.' The other theory is that the pot was black but the kettle polished copper and the pot, seeing its own blackness reflected in the shiny surface of the kettle, maintained that the kettle, not it, was actually black. In any event, it seems that the best, if slangy, retort by the kettle may have been: 'Look who's talking!' Usually the source of the phrase is given as Cervantes' 'Don Quixote' and simply as 'The pot calls the kettle black,' but another version of Don Quixote comes out as: 'Said the pot to the kettle, get away black-face!' Henry Fielding, eighteenth century writer, reverses the roles in 'Covent Garden Tragedy': 'Dares thus the kettle to rebuke our sin!/Dares thus the kettle say the pot is black!' Even Shakespeare used the idea in 'Troilus and Cressida': 'The raven chides blackness.'"
Here's another good explanation.
The only real mention I could find of the possibility of this being a racist term comes from this discussion board. I, personally, don't rely too much on information from discussion boards - there is no reason to believe that any of the commenters are linguists or historians. For all you know, they can be the same dumb people you wouldn't bother to listen to in a debate in person.
Here's a quote that I liked though:
What is it that you (i.e. the objector, as a black person,) find so objectionable about the phrase? Would a Native American object to the phrase "A stop sign calling a fire engine red"? Would an Asian American object to "a banana calling a lemon yellow"?
Actually, I like that quote so much, I'm thinking about using either of those two alternative quotes now. Or, maybe in the interest of avoiding any possibly racist colors I should make up one of my own. How about "That's like the grass calling the pinetree green?" Yeah, I know, kind of lame. And it might insult the leprachauns. Or the Irish. Maybe I should pick a color that can't possibly offend anyone - but what color is that? I'll have to put more thought into it.
So, anyone else? Any thoughts? I may not trust strangers on a discussion board, but I trust my readers. Anyone else think that this is a racist phrase?