Few days ago, Google launches Chrome OS at its official blog, and it quotes:
"Google Chrome OS is an open source, lightweight operating system that will initially be targeted at netbooks."
There's more from John O'Conner's Blog:
"Google Chrome OS will be a slightly more beefy Android OS ..."
And from the FAQ session of the main site, there's a screenshot of this OS (this image does not belong to me):
It's not weird Google target on netbooks, since netbooks has stronger sales recently.
Personally I think it's still too early to judge the impact of it towards Windows OS on desktop.