Yeah...hurricanes is another thing I am worried about too .
Baby Doll is right about the weather equipment onboard. They have both radar and sonar equipment and track stoms from the ship. You'll never hear of a cruise ship being afected directly by a huricane as long as it doesn't have mechanical problems. Ther ships can cruise at approx twice the speed a huricane moves acroos the water. The only danger to your trip from these storms is the posibility of the port of departure being affected and having them cancel your trip.
A good tip on that is buy outside travel insurance. If the cruise line cancels your vacation due to a storm they tipically give you a future cruise credit in the amount of the trip cancelled. By having the outside insurance, you get reimbursed for the cancelled cruise. You now have your money and a free trip!
I book a cruise every year in September, the most active month historically for huricanes (and typically the lowest cost month of the year for cruise pricing). I've never had one cancelled but am prepared if they do.