According to mugglenet.com, who spoke with representitives from Warner Bros, that they are currently planning to make the final book in the Harry Potter series into a three part film.
It was announced last year that the final Harry Potter book would be split into two films,
the first premiring in November 2010, and the second in July 2011.
Warner Bros had this to say: "The book is simply amazing, and we love the people we work with.
Each time we shot a scene we shot too much extra footage because we loved the content so much.
Before we knew it, we had enough content to fill three films."
Although this may seem odd, Warner Bros has already scheduled the film's release for
July 2013, leaving a two year gap inbetween parts 2 and 3.