I've heard a lot of talk on listservs about this sort of thing, but never really paid any attention to it because I never was directly involved. You should tell her to join the YALSA listserv (a listserv for young adult librarians--I'm sure if she googled it she could find it) and post her question there--the librarians are so knowledgeable and welcome anyone involved with young adults to discuss on the list anything to do with young adult lit, including YAs writing it.
And also they should keep an eye out for the HarperTeen fanlit contests, and see if there's anything appealing to her class there. I'm not sure how often they run them.
We've talked about running a contest at some time too, and I'll let you know if we end up doing anything like that. It tends to be high-maintenance for a publisher to do that, though, so at this point it's just an idea that's been floating out there for a while.
There is something else out there that is at the tip of my tongue, but I can't remember what it is. But I think the YALSA librarians would be your best bet at finding a specific wealth of information about that.
Oh, and I got nominated for the NCTE contest as well in high school, and I highly recommend it as a great boost to a kid to be nominated by a teacher. I don't believe I won anything, but the fact that my teacher chose me out of all my classmates to submit my poetry (which, to be honest, sucked, looking back, but at the same time, to be charitable to my 16-year-old self, wasn't that bad for where I was)--anyway, the fact that she specifically took me aside and encouraged me to enter the contest has made a difference to me to this day.