Harry Potter and the Order of the Phoenix
That's the title of the fifth Potter book, set to be released on June 21st, according to this CNN story. The new book has 250,000 words and is more than a third longer than the fourth book, "Harry Potter and the Goblet of Fire", which was already a good-sized book.
As I may have mentioned before, I read the third and fourth books after seeing the second Potter movie in November, and I generally enjoyed them. They definitely are not worthy of the over-concern many people give them.