I've been on Carnival, Royal Caribbean & Princess and have only had the opportunity to enjoy outdoor movies on Princess.
It was last February (2005), but from what I remember they played about 3-4 movies a day, two of which were in the evening hours after dark.
Although our group (7 female friends) were VERY disappointed with our Princess experience, we LOVED the outdoor movies!
The screen was in the main pool area and in the evenings they would put covers over the lounge chairs that had built in pillows and placed blankets at the foot of each one for you to snuggle up in. They also offered popcorn, free of salt or butter, that was awful! (Popcorn shaped sawdust)
I really wish other cruise lines offered this type of experience since I will never sail with Priness again...
But GOOD LUCK!!