In theory, I suppose that you might be able to make a few tweaks, like adding Ubuntu repositories, and hand-configuring a few files, in order to make Chrome OS more like a traditional distribution. But the chance of booby-traps among Chrome's custom code seems a distinct possibility.
Anyway, apart from the satisfaction of figuring out how to wrench Chrome away from its intent, why bother? If you are really that determined to have a locally-based operating system, you will probably sniff around Chrome for a while, then move on to a distribution organized more to your liking.
The overall effect is that, while Chrome OS does not weld shut its hood, it might as well have. Everything about it discourages the sort of tinkering that conventional Linux encourages.
A number of things disturb me about Chrome OS. As implemented by Google, cloud computing requires users to trust in the discretion and reliability of the service provider. And while I have nothing particularly damning in my online files, personally I have a hard time extending that trust.
Nor do I believe -- no matter what the latest promo suggests -- that local computers are any more prone to failure than remote ones. Moreover, if the Internet connection goes down, a local machine can still be used productively. By contrast, if the connection goes down on a Chrome netbook, it becomes completely useless.
More abstractly, some of the assumptions that Chrome OS seems to make are frankly discouraging. For example, the suggestion that files are safest in the hands of a cloud provider seems to abandon the idea that users can be educated to do regular backups. If that is so, then it is a depressing conclusion about human nature.
But, most important of all, for me the whole point of free software is that it gives users the chance to take control of their computing if they want to. Probably it should not force them to take control, but it should present the opportunity.
Yet that is not what Chrome OS does. Instead, it encourage users to accept a generic interface, and to use it more or less as installed. Of course, you can argue that having automatic updates is a convenience, and I am sure that many users are glad of it.
But the point is that in Chrome OS, users are not given a choice. Instead, they are discouraged by the design from exploring enough that they can ever make a choice.
Exactly what license Chrome OS will be released under has yet to be announced. However, the project web page describes it as an open source project, and it appears to act like one. And perhaps it will be released under a BSD license, just as the browser has been. Yet although the software fits all these criteria for free software, if it does not offer users the chance to control their computing, then it has fallen short of the ideal.
Could Chrome OS be the Microsoft-killer that many people hope it will? I suspect not, because I am not sure that the vision behind Chrome of people spending most of their time in the browser or netbooks for light use are accurate.
Yet even if Chrome does succeed in countering the Microsoft monopoly on operating systems, I wonder if anyone will notice the difference.