Passport for Caribbean cruise?

http://a257.g.akamaitech.net/7/257/2422/01jan20071800/edocket.access.gpo.gov/2007/07-3104.htm

This document at the DHS website states that if you leave from a US port and return to the same port, then a photo id and birth certificate are all that will be required. It states

U.S. cruise ship passengers traveling within the Western Hemisphere
would be permitted to present a government issued photo identification
document in combination with either (1) An original or a certified copy
of a birth certificate, (2) a Consular Report of Birth Abroad issued by
DOS, or (3) a Certificate of Naturalization issued by U.S. Citizenship
and Immigration Services (USCIS), when returning to the United States,
under certain conditions:
The passengers must board the cruise ship at a port or
place within the United States; and
The passengers must return on the same ship to the same
U.S. port or place from where they originally departed.

Has anyone else seen this?
Additional Details
There is also a statement on this here

http://www.dhs.gov/xnews/releases/pr_1182350422171.shtm

The departments have also identified unique circumstances for specific groups of travelers that warrant permitting the use of alternative documents.

U.S. citizens on round trip cruise ship voyages that originate and end in the United States may present a government-issued photo ID and birth certificates, Consular Reports of Birth Abroad or Certificates of Naturalization