Sounds similar to a phone call my girlfriend got a couple years ago. Her call wasn't just about a cruise though, it was a few nights accomodations in Florida, tickets to some attractions, and a cruise. They wanted us to pay for the flights, as well as about 300 bucks per person, but everything else was included. We didn't end up doing it, but looking in to it, it seemed like a decent deal. It was for a time share presentation as well though. That was the catch.
This is the group that was offering it to us:
http://www.bluegreenonline.com/
The other similarity with your story is that we entered a draw for the trip, and they presented it to us as if we had won something. It turns out the raffle slip was just a way for them to get information to qualify us for the trip, because they called me a week later and told me that I "won" as well.