U2F support without the U2F Chrome extension
Chrome is white listing Google domains. Non-Google domains has to use the extension for now. However, this will change "very soon" according to Google -- this is documented here and mentioned by a Google developer in this webinar.
Edit: The extension is no longer required with Chrome 41. You can test it out here (Note: When accessed from and older version of Chrome, or not via HTTPS, the site will fall back to using the extension).