The three previous cruises we have been on didn't allow you to bring liquor on board. There are some really funny posts on other cruise line forum boards about how people sneak liquor on to the ship.
On guy puts Rum in a mouthwash bottle and food colors it to get it aboard!
Another hides beer cans inside the 24 pack of coke he has and reglues the box shut!
I'm glad Disney isn't so strict.
I called Disney myself to check out whether it was OK and the cast member said, "as long as it's in your carry on, it's OK" when I asked specifically about Rum and Wine.
We plan on taking a small bottle of rum. They now sell plastic "traveller" bottles, so there's less chance of it breaking in your carry-on.