Yesterday I was watching "Google Chrome OS Open Source Project Announcement":
The "Chrome OS" got demystified, well at least for me. It's nothing more, but also nothing less than a project to throw away some conventions about current systems. Or some people say returning back to the thin client era. Basically "Chrome OS" is (will be?) a damn fast init loader. Init that will load just the things needed to run a browser. Then it is up to the browser to fulfil the consumer needs.
The challenging part will be to add all the HTML5 and other features needed to make browser have all the power of classical desktop applications. Like access to HW acceleration, offline storage, popups, etc. Another challenging part will be to convince people to write real web apps using these features.