According to Warner Bros. Pictures president Jeff Robinov:

"It has been an honor for our studio to be entrusted with bringing J.K. Rowling’s extraordinary book series to the screen, and we have always felt a great responsibility to be true to her vision. In concluding the film franchise, we recognized that Harry Potter and the Deathly Hallows is packed with vital plot points that complete the story arcs of all of its beloved characters. That said, we feel that the best way to do the book, and its many fans, justice is to expand the screen adaptation of Harry Potter and the Deathly Hallows and release the film in two parts. We could not imagine the final chapter of the film franchise being in better hands than those of David Yates."

It’s official! HP Deathly Hallows is gonna be released in 2 movies!