It looks like Google's developer's are hot on the job of making Chromium OS into a consumer-ready Chrome OS. Perviously, if you were to select the Chrome OS desktop tab (the one the far left corner of the browser) it would take you to a login page for an @google.com account. Now it takes you to a page so you can login with your own credentials.
The desktop for Chromium OS is quite interesting, with multiple web-app icons. The icons include Gmail, Hotmail, Yahoo! Mail, Google Calendar, Google Reader and more. This shows that Google isn't attempting to shoehorn users into signing up for their services. They politely provide shortcuts to two more major email providers right on the default desktop.
The Chromium OS desktop also has the disclaimer "UI under development. Designs are subject to change." at the top. It also links users to chromium.org/user-experience, which explains what the Chrome OS developers are doing and how they want the UI for the system to be developed. So what do you think of Chromium/Chrome OS' user interface? Let me know in the comments!
