Apple is now accepting pre-orders for MacOS 9. MacOS 9 is the next release of the OS and probably the last major release before MacOS X Client. According to Apple:
Mac OS 9 is coming, and it's going to make your Mac more powerful—and more Internet-friendly—than ever before. Designed to be your co-pilot on the Internet, Mac OS 9 is packed over 50 new features. Reserve your copy in The Apple Store now.
The Mac Observer Spin: This is a significant upgrade of the MacOS. It has a wealth of new features, many of which will make using your Mac all that much easier. Sherlock II, voice recognition password protection, the long awaited release of Keychain (password storage and organization), multiple users, and more. Definitely worth the US$99.