The good news: Harry Potter is back! With new material!
The bad news: While Rowling is collaborating with a playwright on the script and co-producing the show, she isn't actually writing it. Also, the show will be based on Harry's pre-wizard years, when he was an orphan and lived under the stairs and everything was sad and horrible. No Ron, no Hermione. No Hogwarts.
The Daily Mail believes Warner Bros. will be involved in the play's development, like it was with the "Charlie and the Chocolate Factory" musical. That show takes place in the chocolate factory, rather than Charlie Bucket's miserable pre-Golden Ticket life. Seriously, why isn't the Harry Potter play going to be in Hogwarts? The books seem made for that kind of thing!
Sonia Friedman and Colin Callender will also be producing the play (Rowling said their vision was "the only one that really made sense to me, and which had the sensitivity, intensity and intimacy I thought appropriate for bringing Harry’s story to the stage"). Friedman produced the West End version of "The Book of Mormon," while Callender produced Broadway's "Lucky Guy."
The show is set to open in on London's West End in 2015, though since it hasn't actually been written yet -- let alone figured out the theatre in which it will play -- that may well change.