To be honest the majority of cruise lines do not allow smoking in cabins and it would seem that this attitude will be maintained even enhanced with smoking banned in most parts of the ships. .... Neil.
It greatly depends on which cruise line you are looking at. You need to be specific. Some lines still allow this, although they are decreasing in number, and some don't.
Http://www.cruisegiftstore.com/feature_articles_archive7.htm This is a useful website it lists most of the cruise ships and current smoking policies but these are at the moment under review and could change, but hope you find it helpful.
You can only smoke in your cabin if you have a balcony. But should not flick cigs over the balcony. Beryl. Birmingham.