Turns out the most ridiculous and generic "dumb polack joke"-style accusation about the dimness of Sarah Palin's bulb–that she thought Africa was a country, not a continent–was probably from an interesting and amusing hoax advisor to the McCain campaign–from the nonexistent "Harding Institute for Freedom and Democracy"–going by the phony name (which is also the real name of another minor D.C. policy dude, unrelated to the hoax nope, there is a minor policy dude named "Michael Eisenstadt") of "Martin Eisenstadt."
The New York Times has the details, including some earlier lies he had told (and been caught up on).
The front "Harding Institute" site, with the brilliantly conceived line: "Welcome to the homepage of The Harding Institute for Freedom and Democracy. A Washington-area think-tank in the truest sense of the words…."
"Eisenstadt" on YouTube.
UPDATE: As I said, "probably." The New York Times story certainly reads as if Eisenstadt both was the original source of the Africa story, and recently admitted publicly being so. This AP story states–without any details backing it up, though one presumes he got the Fox reporter to say, no, his source was someone other than "Eisenstadt," and the only hoax was Eisenstadt claiming credit for it. Without a named source, I'm inclined to wonder about that as well. But if so, the mere claiming credit for the leak, as opposed to being the leak, is a pretty weak and lame finale to an otherwise interesting fake career.