Apple announced on its website that Mac OS X Leopard will be available in stores on October 26.
Engadget took a look at some of the new features of this OS:
Users who bought Apple machines from October 1st on can
participate in Apple's Up-To-Date Program, which provides free Leopard
upgrades (for $10 shipping).
Boot Camp's beta Assistant software expires at the end of 2007, meaning
Tiger users that want to continue editing / creating Windows partitions on
their Macs need to do so before January, or upgrade to Leopard. Post-January
you'll still be able to boot to the partitions you've created, though.
Users shouldn't expect expanded sync capabilities between Mail.app and the
iPhone, although it looks like you'll be able to read iPhone notes on your
desktop machine now.
File system is, indeed, still HFS+; OS X now supports read-only ZFS, as