Chrome has recently been open sourced by Google as a developer preview. Its very young, clearly has some issues and needs serious work, however it is usable and lots of people have managed to get it running in a virtual machine or via a USB key.
Chrome OS is clearly based on Ubuntu(if you press Ctrl+Alt+T to open the terminal, you can see the Ubuntu Karmic development branch message) meaning hardware support should be excellent. However, its been heavily stripped down
For most people, Wifi doesn't work. Without Wifi, Chrome OS is pretty useless as it relies heavily on "the cloud" for most of its features.
My laptop uses the Intel 5100 wireless chipset, and I was dismayed that the wireless didn't work out of the box, as every Linux distribution has supplied drivers with ease. Installing the firmware seemed like it might be difficult at first, as the root file system is read only. However, getting it working only took two seconds, and if Wireless works out of the box for you in Ubuntu Karmic, it'll also work in Chrome OS. Note: Your primary hard drive will need to have Ubuntu Karmic on it for this to work
Login using the default details (username: chronos | password: password)
Open a terminal with Ctrl+Alt+T - you should be logged in automatically, if you aren't use chronos and password again to login.