Pottermore club as in the spot on Fanpop? That's up and running.
But if you meant Pottermore the site... Well, no one really knows. At first they said end of October, but then the developers realized it had way too many bugs and beta testing needed to be extended. On Pottermore Insider they stated that the site will not be opening to new users in the immediate future, but please know that we will open registration as soon as we can. Take that however you want.