According to CNN, Harry Potter and the Order of the Pheonix will be released on June 21st, 2003 worldwide.
They even have a bit from the opening of the book.
The hottest day of the summer so far was drawing to a close and a drowsy silence lay over the large, square houses of Privet Drive ... The only person left outside was a teenage boy who was lying flat on his back in a flowerbed outside No. 4.
J.K Rowling is so hot. Thanks for the heads up Loney_Hat!