So if all that has you scratching your head and thinking "Hmm, not exactly a compelling feature list" then you'd probably be justified. There are few big ideas in Leopard, and most of the ones that are there have been nicked from Linux and repackaged. But it's not all doom and gloom, as there are some very nice 'under the hood' improvements to the OS that users should appreciate.
The first is the appearance of Core Animation. This is another one of the Quartz technologies, which include Core Video (Apple's video processing libraries) and Core Graphics (the rendering engine of OSX). Animation allows for the easy creation by developers of gorgeous-looking interfaces, which Core hands off to the GPU to render. Apple was the first big player to rope the GPU into rendering desktop interfaces with its release of version 10.2 of the OS, and the gradual expansion of Quartz technologies has been a hallmark of its development. We like efficiency, and more GPU rendering means more CPU power for everything else.
Like Vista, Leopard places a new emphasis on security in this age of the internet, and makes a few welcome tweaks. The first is Sandboxing, which transparently virtualises certain applications to prevent any malware or viruses from hopping onto the OS. The new versions of applications such as Bonjour, QuickLook and Spotlight are now severely restricted in their access to your system and the permissions with which they run, meaning that malware can't exploit their access privileges.
However, Security is definitely hit and miss for Apple as its new Firewall is arguably a step backwards. Unlike Vista (and even Windows XP SP2), the firewall is not active by default which, in this age of viruses and worms, it really should be. More worrying is that even when the Firewall is set to block all incoming connections, it doesn't. Now you might say that modern NAT routers are protection enough - but with Apple's laptops designed to roam out and about wirelessly, a firewall that the user controls is surely an essential OS component, and is certainly one Apple hasn't nailed yet. Those on both sides of the pixel-per-inch debate will also enjoy Leopard's support for resolution independence - even if such support isn't exactly visible yet.
Apple has always worked at 72 DPI for its computer displays, but the new 17" MacBook Pro runs at 100 DPI, to the annoyance of some and the love of others. Leopard allows developers to scale up applications and scale them down in size at the user's will, meaning that as display pixel density increases over the next few years, users can maintain control of their eyesight.