No irons provided and they discourage the bringing on of irons due to fire hazard. They do offer pressing service (in addition to cleaning/laundry service) which is so worth the cost.
You just need to give your garment(s) to your cabin steward and he/she will have it pressed and return it to your room. I had a floor length full skirt one time and sent it out to be ironed and it was only $4 or $5.
It is so worth the money to not have to mess with it myself.