Well, but this is the paradigm shift that Google (cloudsters) have talked about for a couple of years now. Chrome is not so much OS as ad medium. Right now, it's just a foundation, making up in speed what it (purposefully) lacks in extras. When the Google guys say the browser is the OS, they're not joking: they've created a free, easy-to-use, efficient browser that pushes users to the Web -- and Google's ads -- as quickly as possible. In return for text ads, you get "free."
With Google's Chrome OS business model, the OS isn't a revenue-generating product. It's hardly a commodity per se. It's not even a service, as Microsoft's Office Web apps try to be. Under Google, the OS is a medium, like television, radio or the Internet. That's the revolutionary idea, and one that we should take time to ponder.
Being open source, Microsoft would be smart to simply build its own version, inserted IE where the Chrome browser is. The only other option is for them to sue the socks off Google in Federal courts (like they've done by funding SCO) for the next decade or two. This is indeed an interesting time to be computing!