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.
my pug Mei Mei
I took my own hair dryer when we cruised on the Victory (even though there are dryers in the bathroom) because I typically shower first and then dry hair/put on makeup while hubby showers. With the hair dryer being in the bathroom, it made it more difficult to dry hair my hair while my husband was using the bathroom. Might want to take your own if you're traveling with someone else.
If you are looking for a GREAT travel hair dryer you should look into the one from Brookstone, its a bit pricey as hairdryers go, but it is great, its small and powerfull, folds up into its own nice little bag. I have the Ion one.