Apple has today announced that the release of MacOS X 10.5 Leopard will be delayed until October due to the development of iPhone.
iPhone contains the most sophisticated software ever shipped on a mobile device, and finishing it on time has not come without a price — we had to borrow some key software engineering and QA resources from our Mac OS® X team, and as a result we will not be able to release Leopard at our Worldwide Developers Conference in early June as planned.