MSC is indeed doing Caribbean cruises this year. In fact they saw your post and wrote to me.
Good morning. I hope all is well. I wanted to contact you in regards to a post on Thursday, see below, about Caribbean cruises for 2011. They’re listed on our web site at http://www.msccruisesusa.com/destinazioni/2009-caribbean-cruises to select the 2010 or 2011 season. Then, you can select specific dates for cruises in the months posted.
Well....that link didn't quite work, but I did manage to find it by "cruising" their site (pun intended). However, it shows only one ship on March 6, 2011; and when I pull that up it doesn't tell me a whole heck of a lot. I guess this cruise will require a TA in order to research.