It takes an extreme amount of confidence to pull off a dress like that. I give women a lot of credit for confidently strutting their stuff in a revealing dress. I'd feel extremely shy if I had to do that. I guess what I'm trying to say is that women, we see you and we applaud you. For a high school dance, however, this may be slightly too revealing, even if she has that fuzzy shawl to cover some of it.
I'm not sure how prom dress regulations vary from school to school, but I know of some that would have probably took issue with this dress. More power to her for going with it, but schools get very weird about women's dress codes. Then again, it would be pretty rude to turn someone away after spending all that time getting ready.