Read the story linked to in the first post, please. It doesn't say the "Palin quotes are a hoax." It says that Martin Eisenstadt's taking credit for leaking the quotes was a hoax.

There is no Martin Eisenstadt, it's just a false name on a blog. But the story about Palin thinking Africa was a country didn't originate on his blog, it originated with an unnamed source within the campaign who spoke to Fox News. The phony "Eisenstadt" then falsely claimed credit for the leak.

The leak itself was real. This does not necessarily mean the story is true, but the leak was real. The fact that a hoaxer later claimed credit has no bearing on whether the quotes were accurate.