What is Leopard?

Leopard is Apple's latest version of the Mac OS X operating system. Leopard has been designated a version number of 10.5. Leopard is the 6th version that Apple has released since early 2001. Leopard contains more that 300 new features when compared to Tiger, the prior version of Mac OS X.

Mac OS X Leopard Box - Courtesy of Apple

Some of the new, noteworthy, and/or improved features of Leopard include:

Boot Camp - Run Windows XP and Windows Vista on your Mac at native speed with full compatibility. Boot Camp was a beta (test) software in the prior Intel-based version of Mac OS X, specifically Tiger (version 10.4)
Spaces - Organize your activities into separate spaces and easily switch from one to another.
Time Machine - The automatic backup solution built into Mac OS X. Time Machine automatically makes copies of everything on your Mac including documents, digital photos, music, movies and TV shows, and documents. Recovery of your files to a specific time is the past is now possible!
Quick Look - with a single click you can easily view the contents of files without ever opening them. Look into text files, PDF documents, images, movies, Keynote presentations, Microsft Excel and Word documents, and Mail attachment. Quick Look even works in Time Machine.
Downloads Stack - Find your downloads quickly in one dedicated stack that's easily located in the Mac OS X Dock.
Finder - a new and improved Finder makes browsing files on a Mac easier than ever. You can flip through files using Cover Flow or using an iTunes-style sidebar. Finder now allows you to participate in an interactive screen sharing session with other Macs on your network.
Synchronize with Yahoo! - Synchronize Address Book on your Mac with your Yahoo! address book