OS X Snow Leopard seems to do nothing really new. And yet, it could be their most important OS since 10.0.0. Updated the Bad Stuff section.
Snow Leopard, as a follow up to Leopard, is almost absurdly insubstantial at first glance. The new operating system takes the same old boring, every day tasks like opening files, for example, and makes them happen subtly faster. But that performance is not being utilized by any third-party programs right now. And there are practically no new first-party programs by Apple. Nope, mostly just rewritten old ones and dozens of little interface tweaks. Some fanboys will ask, incredulously, "This is a new operating system?!" Those people are missing the point.
On deeper inspection, Snow Leopard's inconspicuous aspects—performance squeezed from underused CPU multicores/GPUs and basic UI tweaks—are found to be the kind of refinement generally reserved for virtuosity. These speed optimizations are deep, reminding me of when a master martial artist puts the entirety of his weight behind a strike (while a neophyte would flails his limbs like a henchman in a Bruce Lee movie). The little UI tweaks are no different than when a great sculptor's chisel works to remove everything non-essential during the final steps on a statue. Challenging 30 years of ever more bloated software tradition, the changes here are about becoming a more effective middleware between the media and the hardware, reducing friction while becoming more useful by, well, being lighter, less visible.
And if you think that's bullshit, well, I can't say you're completely out of your mind, but there's always the consolation that this OS upgrade costs about the same as a used Xbox game.