eweekeurope has done a pretty decent review of the Chromium OS BETA. Here are few interesting quotes from the review

Google does not plan to release Chrome OS as a stand-alone operating system, but instead plans to partner with OEMs to deliver Chrome OS on netbooks and other devices. But Chrome OS is an open source project, so it is possible that others will build versions of Chrome OS that can be downloaded and installed on any system.

Once Chrome OS is launched, you see what is essentially a standard Chrome web browser screen. However, a unique button appears in the upper left-hand corner of the screen. Clicking this button launches the Applications page, one of the few aspects of this developer build that is different from the Chrome browser. Within this page is a pre-set list of applications that can be launched within Chrome OS. These include the Google applications you’d expect, such as Gmail, Google Apps, Calendar, Picasa and YouTube. However, the list also includes Web applications such as Yahoo mail, Pandora, Hulu, Facebook and Twitter.

Read full review here