That MLK Jr. freed the slaves is, apparently, a very common misconception. Why? Chris says: "it shows how poor the teaching on race issues is. Teachers don't really talk about race in the present, and it creates major problems for talking about the past."
I think that's probably true, but I think there's also a simpler explanation. I was watching my tivoed episode of Studio 60 on the Sunset Strip tonight, and at some point two of the main characters go out to see a black stand-up comedian. They think he's so funny and smart that they hire him on the spot as a writer. Here's an approximate paraphrase of one of his jokes:
"I think about African American slaves, and about how we stacked up against other slaves. Look at the pyramids -- those were built by slaves. No one ever told us we could use geometry!What????
And those slaves, they got Moses. Now, I'm a big fan of the Emancipation Proclamation and all. But they got a burning bush. We got a memo: 'Free at last, free at last, thank God Almighty, we are free at last.'"
This coming from what's supposed to be the pinnacle of network TV show writing. If they think MLK freed the slaves, what chance is there for my kids?