I don't have personal experience but on our last cruise (1/17/09 - Magic) the family at the table next to use (they weren't table mates, but were close enough to be and we wished they were!!) had a DD who was allergice to nuts, eggs, and milk...talk about scary!
and she could just breathe it and have the reaction.
All the servers were fantastic with her, especially the Head Server, who would bring her anything she wanted. They prepared it seperately in another kitchen (as PP stated) and would go up to Plutos and get her chips, hot dogs, etc. They would find fresh veggies that were not cooked (she didn't like cooked ones) like carrots, etc and always had fresh fruit for her. She has a HUGE smorgoshboard of food!
- it was good to see.
The same family had a piece of luggage lost, it happed to be the one with all her soy milk in it (since she was allergic to milk) and they found soy milk for her and had it available to her 24 hours a day. They found the luggage and had it flown to St. Maarten (our first stop).
The little girl was so sweet (no more than 3 YO) and would come over and take our picture with a pretend camera she had. I was scared she would breath in something from our plates!! But her DM watched carefully and all was perfect.
Hope that helps, just want I noticed, but again no personal experience.