But JKR HAS RELEASED BOOK SEVEN'S TITLE!!!
If you want to be spoiled like I was, it is Harry Potter and the Deathly Hallows. Seriously, I was reading my friends list, and I have leaky_cauldron's news updates on my friends list. And... I got spoiled because the release of the title came after (i.e. I read it first) the one about the little game you play on JKR's website to find out the title.
Excuse me while I render myself incoherent.
Edit: If you're stuck, here are spoiler-free instructions on how to get in. I don't recommend clicking the comments or my lj-cut if you want to avoid spoilers for the obvious reasons.
Now the real question was whether this was title one, two, or three.