With Apple's latest Operating System, you get a fancier looking QuickTime with screen capture ability, and the network drop-down menu shows the strength of each network. Other user-interface features include a black menu that appears when you alternate (right) click something in the dock instead of white. Also, the stacks allow you to do a little bit more viewing. Some behind-the-scenes improvements such as Grand Central Dispatch are imbedded deep in the code to take full advantage of your processor and even use your graphics card for computing power. If that's worth 30 bucks to you, then gopher it, otherwise, it's just a new name.
