Browser auto-fill phishing
Wow, great demonstration. I'd never thought about this being exploited. I wonder if the fix could be something as simple as the browser only allowing non-hidden [Edit: "not visible to the user", I should have said, as this does not appear to auto-fill <input type="hidden"> ] fields to be auto-filled. Otherwise, a warning about what auto-fill information (IE "Your name and credit card information are going to be submitted, continue?") has been  filled in would be a nice touch. Maybe a browser extension could accomplish this?