I asked this question earlier about the Spirit (we're sailing in December).
I felt bad asking because I thought I remembered the answer being on the Carnival website, but couldn't find it!
Well, some nice Forum member answered my question and not two hours later, I found the information on the website! **....Here it is for you:
A hair dryer is provided in the bathroom (Destiny, Triumph, Victory) or at the desk/vanity in the stateroom (Spirit, Pride, Legend, Conquest, Glory, Miracle, Valor). Hair dryers are not provided in the staterooms of all other ships.