Yes, you'll find a hair dryer on the wall over the desk, seemed adequate as long as you don't have extra long and think hair to dry. There are also extra outlets, not a lot, if you have camera's that you need to plug in too may be wise to bring a power strip.
Irons are not permitted on any ships - Fire hazaard. However, Princess ships usually have a Laundry room for your convenience. Pack with light plastic dry cleaner bags to reduce wrinkles, especially on evening outfits. It really does work.
I used to pack my travel iron, but no more, never used it. If you have a garment bag, pack your "good" clothes in that. For other clothes i always steam them in my cabin's shower if they get wrinkled, as for the hair dryers, I bring my own because i have very thick hair, and it would take forever using the cabin hair dryer(not to mention -burning it up!) Also there are laundry rooms w/irons on the Dawn and a laundry service that will press your clothes for you for a nominal fee.