It doesn't say that it has to be a senior but they all seem to be. Here is a list of all of them http://en.wikipedia.org/wiki/Iowa_Miss_Basketball , I would bet that they also have to play more than 8 games on the year but it doesn't say that either.
I would say that is a pretty safe bet at this point. No clear favorites at this point for next year or am I missing something? Lot of good players in that class though.
Nothing against those that have won it but the gatorade player of the year award is a joke. Way to biased towards the big schools and the list has some pretty notable omissions. http://www.gatorade.com/poy/winners.aspx?sportcode=GK