Can the U.S. assert copyright? I thought all work product of the Federal Government was in the public domain (e.g., http://en.wikipedia.org/wiki/Copyright_stat

Can the U.S. assert copyright? I thought all work product of the Federal Government was in the public domain (e.g., http://en.wikipedia.org/wiki/Copyright_status_of_work_by_the_U.S._government http://en.wikipedia.org/wiki/Copyright_status_of_work_by_the...)