Here's a recap of the current (& changing) smoking
policies of most cruise lines in US, Caribbean & Europe:
http://www.cruisecritic.com/articles.cfm?ID=225
Many (or most) of the Carnival-owned cruise lines have changed
their smoking policies to take effect between 12/1/11 & 1/15/12,
depending on the line.
You will still be able to smoke on your balcony on Carnival or
Holland America next year (NO smoking in the cabins anymore),
but of course you have to spend more to get a balcony.
Pesonally, I didn't like smoking on the balcony - too isolated.
I much prefer to sit on the back of the open Lido deck (where
one can still smoke cigars on Holland America & other lines),
and actually interact with other passengers.
The prohibition of in-cabin smoking, however, will mean that my
upcoming cruise with Holland America in November will be my
last one with them. This after averaging a cruise every year
for 15 or more years. If I can't light a cigarette in my room,
I'm not booking the room.