The deathly hallows referred to in the title are most likely the horcruxes. The HP site Leaky Cauldron has been going nuts over this, and I think they might have found another horcrux referenced in BOOK ONE of all places.Explanation:

Hallows are the objects sought by Holy Grail questers, which usually involve a spear/stick/pole, a sword, a cup, and a stone/pentacle. These are also the four tarot card suits. Not a coincidence. And of course, book 6 was filled with explicit tarot references, use of the cards, lightning-struck tower. Now, someone noticed this before, and speculated that the four horcruxes that belonged to the four Hogwarts founders correspond to these suits. We already know Gryffindor’s is the sword, Slytherin’s locket (pentacle), Hufflepuff’s cup. So Ravenclaw would be a spear or a stick. Or a wand. And there’s a part in book one where Harry sees a single wand laid out on a faded purple pillow in the window of Ollivander’s shop. And the shop was raided in book 6. This would be kind of a wild theory EXCEPT for the use of "hallows" in the title now, which is linked really strongly to tarot.

So there you have it. Ms. Rowling must be having the biggest multiple joygasm just imagining how much her legions of obsessed Potterphiles are clawing at the walls trying to decypher a meaning for the new title and the possible plot twists of this book. That Woman is a true witch.

I do advice you that you do not look for info on this new book on Harry Potter fan sites, because the speculation has gone into overdrive on every corner of the internet and you might stumble into some ideas and possible spoilers that could ruin the whole book for you (not to mention the previous ones if you haven’t read any of them). It’s a very nasty feeling, and you’re hearing this from someone who found out who dies in book 6 way before getting to that part while browsing some stupid goddamn blog who fortunately is no longer online.

Anyway what the hell are you waiting for? GO PREORDER IT. NOW.