I've looked around a bit and can't seem to find anyone else having this problem.
I downloaded the new Chromium OS from the Dell site, fired up PuppyLinux on another laptop, performed the dd command, but the USB stick won't boot.
It doesn't seem to show as a bootable device. There's an entry in the F12 menu for a "removable device" but not USB.
Since I have OS X installed, is it possible that it's interfering with Chrome?
I have a new 8GB stick I bought specifically to try Chrome and I'd like to get it to work.