Apple's new OS, Leopard (Mac OS X 10.5) appeared for the first time in public today.

It's the sixth version of Apple's Vista-vaunting OS to debut so far, and includes a range of new easy-to-use features, including Time Machine, Apple's new user-focused backup and retrieval utility.

Leopard includes what Apple terms "industry-first advancements" in Mail and iChat. Mail now features Stationery, Notes and To Dos, while iChat includes Photo Booth-style effects (the ability to "place" yourself in any photo or video as the backdrop for your chat) and live presentations of iPhoto slideshows, Keynote™ presentations and videos.

"Breakthrough features like Time Machine and Spaces are good examples of how Mac OS X leads the industry in operating system innovation," said Steve Jobs, Apple's CEO. "While Microsoft tries to copy the version of OS X we shipped a few years ago, we're leaping ahead again with Leopard."

Time Machine automatically backs up everything on the Mac to an external hard drive or Mac OS X Server. In the event a file is lost, users can search back using an intuitive, time-based visual display to find and then instantly restore the file - with just one click. Time Machine can restore anything, from a single file or photo to everything on a Mac.

Another new feature, Spaces, is a productivity-focused extension of the concept of a user identity. As explained by Apple, it is an "intuitive new way to group applications required for a given task into a 'space', then instantly switch between different spaces to bring up the specific applications required for that given task."

The company explains: "Users can get a bird's eye view of all their Spaces and choose where they want to go next with just one keystroke or click of a mouse."

iChat has taken another step forward. It can now place user-selected images in the chat background, they can also place videos and use iChat Screen Sharing to share their desktops with others, boosting project collaboration.

Another new feature - iChat Theater, lets users share an iPhoto slide show, a QuickTime movie or a Keynote presentation within an iChat window.

Leopard's Mail offers new advancements, too, such as pre-made email templates, note-taking, To Do lists (which integrate with iCal), RSS news in Mail and Smart Mailboxes for topic-focused message-watching.

iCal 3 adds group calendaring capabilities, event drop box, and standards-based CalDAV support.

However, Apple isn't completely focused on delivering consumer applications. The new OS will offer native 64-bit support. This will allow applications to exploit 64-bit processing while maintaining full performance and compatibility for existing 32-bit OS X applications and drivers.

The company also promises "enhancements" to Boot Camp, Apple's innovative technology, previewed as a public beta in April 2006, that makes possible to run Windows natively on Intel-based Macs.

The company also promises more accurate and faster Spotlight searching. In its new iteration Spotlight will also allow users to search across network-mounted folders on other machines.

Additional new features in Mac OS X 10.5 include: a new Movies Dashboard widget for movie times and Web Clip for clipping any part of a web page as a live widget; new parental controls including curfews, time limits and remote administration; Core Animation, a new graphics technology that makes it easy to create stunning visual effects and animations; and major enhancements in Universal Access, including improvements in VoiceOver, Apple's built-in screen reader.

Users can also look forward to security enhancements including anti-phishing protection and new development tools.

For developers, Apple is offering: full 64-bit support in Xcode; DashCode, an easy way to create new Dashboard widgets without writing a line of code; and Xray, for optimising application performance.

Leopard ships this spring, Apple said.