Since taking the second W.O.M.B.A.T. I have a new theory about when we'll get the Book 7 release date. The exam results all mentioned that
"the third and final W.O.M.B.A.T. [will be] in a few months' time."
In addition, the HBP release date was announced just before Christmas. Putting two and two together--just before Christmas is also in a few months time--I think part of the reward for the third W.O.M.B.A.T. will be finding out the release date.
Or maybe I'm just being wishful. But really *cute little kid whine* it's all I want for Christmas....