There's already a standard: POSIX.
The thing with OSs is, like any technology, one size does not fit all. Since it's not a real big deal which OS you use, as long as you can intercommunicate with others, I'd think that a government issued OS would be pretty pointless.
If there's anything to nationalize, it's something like Java. It operates only a portion of a computer, but it's a portion that is very generalized. OSs are not very all-purpose (though the vendors say they are), while machine neutral execution tools like Java are more all-purpose.
John Kawakami johnk at cyberjava.com http://www.riceball.com/ethnoveg - the ethnic studies + vegetarianism list