They did on our October 2011 Dream cruise. We also got the small 3 inch DCL vinyls and had Captian Gus sign the back of them during the captians signing. The kids love them. He had a silver and black sharpie with him so any colored vinyl would work.
How did the 3" ones turn out? It seems that it would be such a small space for the signatures....plus some of the characters sign so big!!