yes you can, I would recomend taking cans though. You can put it in a hard suit case or in your carry on. Everyone makes such a big deal about this. As long as you don't anounce it to the security or to the staff there should be no problem. In fact my parents (who are very cheap) have taken on a hole suite case full on one of the longer cruises. Hope this helps.
I have been on 8 Carnival Cruises and have been fortunte enough to drive to the port a few times. I have taken a small carry on full of water, sodas and liquor. Now, the brochure for many years has stated that liquor is not allowed. But I have discreetly taken it in a plastic flask or disguised it as soda or snapples iced tea. Upon reading my documents for my last cruise in May 2003 - they stated that NO BEVERAGES WERE ALLOWED at all. I dont think they will enforce this new rule because I'm sure lots of us past cruises will not be happy.
If any one has had any recent experiences with this I'd like to know also.