Great job on the first tests of a Kindle, Nate! Let's see some karma for this guy!
Good news about the non-DRMed Mobipocket USB'd to the Kindle and also the DOC conversion with images. You might try uploading an HTML with images, too. And more than one person on the forum has mentioned that it could be done with a PDF although I don't recall seeing that anywhere in the manual or on Amazon's site. But you might try and let us know the result.
Too bad about the Washington Post. That would have been really neat to wake up and see the digital equivalent of the paper version every morning.
Hope you're having fun.