Reload the iTMS front page and look in the middle of the page, it should be right there. It will take you to your education Apple Store page or the Apple Store front page if you don't have an education page. The Apple Store isn't updated with the promo yet, but this shows that the Back to School '07 promo is indeed launching tomorrow.
Nope not there. I wonder if its because it's not officially 12 o'clock here yet?
UPDATE: Restarted iTunes and sure enough there it was!