The next release of Apple's operating system, Mac OS X 10.5 Leopard, was originally scheduled to ship in the spring. However, Apple announced back in April that it was postponing the OS until some time in October in order to get the iPhone out in time.
With the first half of October now behind us, Apple has finally announced a release date for Leopard: October 26. The OS is already available for pre-order from the Apple Store for $129, and Apple says Leopard will become available both individually and pre-loaded on new Macs at 6:00 PM (presumably PST) on that date.
Mac OS X 10.5 Leopard will bring a redesigned desktop, a new Finder with iPhone-like Cover Flow functionality, full support for 64-bit systems, built-in Boot Camp software for dual-booting with Windows, a Shadow Copy-like backup tool called Time Machine, and a virtual desktops implementation dubbed Spaces. More information about Leopard is available on the Mac OS X page on Apple's website.