Chrome OS code available today 11/19 (release next year?)
The press conference was for the releasing of the source code (Chromium OS) www.chromium.org/chromium-os, meaning the code is available for developers to download and contribute but google's Chrome OS won't release till next year.
Chrome/Chromium OS is for x86 and ARM. The OS aims to have data and apps in the cloud ("everything is a web application"). Its suppose to be secure (the "user never installs binary" Google does). The OS looks like an extension of the Chrome browser e.g. applications == tabs (see the demo in the press video).