No, for the following reasons:
- it's the second anniversary of the London Bombings. It would be rather disrespectful for a British author to release such a hyped book on the day that the media's focus should be on commerating the dead. It could also cause problems for Londoners who want to peace and quiet to grieve and visit the bomb sites when there's all the fan fare for the book.
- it's too late to just announce such a release date now. It's only six months away. The majority of people who collect the book at midnight are teens and adults, not children, and they need time to plan holiday leave/ask for time off from work. A 07/07/07 release date just announced now doesn't give many folk much time.
- it's too soon for the book to be released. Bearing in mind that JK Rowling told us last year that she wanted time off to spend with her new baby before beginning to write the book in January 2006, that leaves her less than a year to finish it (yes, the book supposedly won't be released until July but you need at least six months for editing, printing and delivery). I don't think either JKR or readers want a rushed book.
- it's been too quiet. Neither JKR nor her publishers have given any hint at all that the book will even be released this year. When HBP was being released in July 2005, there were whispers by early December 2004 that the book was ready for release soon (and JKR made a formal annoucement in mid-December). This time, there's been nothing aside from rumours by over-excited fans and greedy book stores who obviously want people to pre-order from them