Apple has done a perfect job advertising iPhone, but its development is not finished yet. In order to fulfill its promise and ship iPhone in late June, Apple had to borrow manpower from its Mac OS X team. This will result in a delay of Leopard operating system.
Apple will not be able to release the Leopard OS at Worldwide Developers Conference in early June, as planned before. The "near final" version will be demonstrated at the conference, and beta copies will be given.
The new release date for Leopard is October, this year.