As nobody seems to be talking about Chrome OS, here's an update:
http://chromeossite.com/2010/08/05/cloud-print-appears-on-chromium-os/

Here's also a way to test it easily:
http://chromeossite.com/2010/08/12/hexxeh-releases-chromium-os-vanilla/

cloud print is old.

Yes. It's mostly about the implementation (which landed recently in trunk).