Google just patented Chrome OS, but the tone of the patent is much more than that. Google may have, in fact, received a patent that covers client cloud operating systems in general.
The patent is entitled "Network based operating system across devices" and was filed in March of 2009, about two months before Chrome OS was officially announced. What makes this patent special is the fact that it covers virtual all aspects of "providing an operating system over a network to a local device" in a manner that would apply to any cloud OS that uses software other than a web browser. And even the web browser, as an entity that is regularly updated and would, conceivably, fill the role as operating system framework, would be touched by this patent.
As malicious as this patent may seem, it is more likely that the patent actually reveals Google's intent to tie hardware and software experiences much closer together. If the patent is enforceable and not invalidated due to prior art that could be claimed by Oracle because of its NC and Sun's JavaStation, the patent (as well as the recent buy of Motorola) highlight that Google's software is moving much closer to hardware.
It is somewhat dazzling how Google could get a patent on such a general approach. However, if Google can claim the rights to it, the question would be how Microsoft can react. Essentially, the cloud OS for client computers is now patented.