Maybe too early for a definitive answer, but since Chrome OS is open source now, somebody might have an idea of minimum hardware requirements.
It is highly doubtful that ChromeOS will support the XO:
Of course it is "possible," in theory, if someone wants to throw a few hundred thousand dollars at the problem. But what's the incentive to spend the money to make a circa-2010 operating system run on a circa-2007 laptop that was never a commercial success?
As it is going to be open source, I don't see why not... However, out the box - I don't think so.
The people behind OLPC are not on the partner list and the specification are not at all sufficient from what I heard in the webcast earlier today.
There would need to be a considerable amount of customization to the software in order to make it handle the hardware.
For one, the much-loved screen technology has a very odd dot pitch--running rdesktop to a Windows will reveal that. It also runs at 1200x900.
Only "certain" SSD chips are supported--and I'm fairly sure the XO is not using one of them. The Marvell wireless chipset will need to be handled, as will the power savings functions and the definitely-not-qwerty keyboard layout.
Speaking of that layout, the "rotate screen" button and the screen backlight / mode switches would also need to be custom coded.
And Chrome may not be optimized for an AMD Geode 433mhz--it'll probably be optimized for whatever Intel Atom 1.6 is in vogue at the time.
So...quite possible, but also not likely without a community-led effort.