I just phoned NCL. The guidelines have been revised last year. As of November 2004, the passengers can bring wine on board.
Soft drinks: Yes
Liquors: absolutely NOT
Wine: Yes, provided:
1. the wine is not on the wine list
2. $15 corkage fee
The corkage fee applies whenever the wine is opened, whether in the restaurants or in the cabin.
I think the wine in the room will also have corkage fee, if they found the opened bottle in the room, probably. That says, if you open your wine in the room and didn't finish it, there's a chance the cleaning crew will report it to the front desk and they will charge you the corkage fee.
So, do a research of how much is the wine in the store and plus $15, see if you can get a comparable wine from the list. For example, I'm bringing a botttle of new Beaujolais, it's $10 from the store, plus $15 will be $25, and there's a Beaujolais-villages from Louis Jadot that sells for $26 on NCL. For that, I might just buy the wine from NCL.
I just returned from an NCL cruise and corkage fee seems to be strictly enforces. People were told that you may bring 1 bottle of wine aboard in carry-ons luggage. If you did so, you had to either surrender the bottle at embarkation and pick it on leaving the ship or pay the corkage fee at that time. I don't know how they would hndle wine provided as a gift by your travel agent and placed in your cabin pre-cruise. Although not allowed, I know for a fact that sometimes people pack alcohol in checked luggagge and consume it in their cabins. Just store it locked in luggage or safe.
I just got off an NCL Cruise. All luggage and carry ons are Xrayed and you are required to walk through a scanner similar to those used in a airport. All booze is confiscated. The only way you will get it in, is in plastic bottles carried on your body or in mouthwash bottles in your luggage. If you BYOB wine bring large bottles 1.5L to 5L jugs to maximize on corking fees. The wine will be served to you at any of the bars or restuarants on ship upon your request, by the glass to you and friends and recorked until you use it up.