If you want it corked in the dining room they charge you a fee, but if you want to drink it in your cabin feel free to!
Carnival Dream for Thanksgiving
Eastern Caribbean- 11/20/2010
Carnival Ecstasy (4 Day Baja Mexico) 2003
Carnival Pride (7 Day Mexican Riviera) 2007
Carnival Spirit (8 Day Exotic Mexican Riviera) 2007
Carnival Freedom (7 Day Western Caribbean) 2008
Carnival Elation (4 Day Baja Mexico) 2009
Carnival Spirit (7 Day Southbound Alaska) 2009
The simple answer is NO. They will not allow you to bring any alcohol onboard or let you bring your own wine into the dining room for a corkage fee. If they find it in your luggage they will confiscate it and could even revoke your embarkation with out a refund. IMO it is not worth the risk.
Fantasy - Bahamas 4/96
Rhaposdy - S Caribbean 11/97
Jewel OTS - Western Europe 9/07
Mariner OTS- W Caribbean 10/08