The Pottermore beta has been going on so long and the opening delayed for so long that I, for one, had almost forgot about it. But today, the site announced that the interactive Harry Potter site will be opening for everyone in “early April.”
Part of the holdup, it seems, has been a move to “an entirely different platform” that should (hopefully) hold up to the expected amounts of users. (The beta was/is notoriously slow.)