DW and I sailed for the second time, this time to St. John/NB on 8/30/07.
Embarkation at the Manhattan Cruise Terminal (in New York City, there is a new Brooklyn one, too) was surprisingly quick compared to Miami 2 1/2 years ago. We arrived at around 1:15 p.m. and were in our cabin no later than 2:50 p.m.
Being non-US citizens we had to abandon our passports. We did not need them going ashore in St John, and got them back during the debarkation process (see below). On our first cruise (also Carnival), we were allowed to keep our passports. I guess, the rules have changed.