Ars Technica is an amazing computer enthusiast website, and they often have the best in-depth reviews of each new incarnation of Apple’s Macintosh operating system. Leopard (version 10.5) was released last Friday, and Ars covers not only new features, but new OS internals and predicts what it means for the future. Most of the review is technical, but the author (John Siracusa) hits many of the user interface points right on the head.
I won’t go into too much detail here, but the author certainly has an eye for these things. For example, his review of the new “special” folder icons (such as for Documents, Movies, and Applications) that look like this:

John Siracusa at Ars Technica writes:
When it comes to at-a-glance identification, the difference is striking. I find myself literally squinting at the Leopard special folder icons, as if I’m constantly not seeing them clearly. You can find a more rigorous examination of the new folder icons at Indie HIG (a site whose mere existence is a blot on Apple’s recent user interface record).
Poorly designed folder icons aren’t the end of the world, but it’s the context that’s so maddening. Here’s an interface element that maybe could have used some freshening up, but it was far from broken. Apple’s gone and made it worse in a way that’s obvious in seconds to anyone who’s ever given any thought to interface design. It boggles the mind. The rumor is that Jobs likes them. Great.
He doesn’t need to understand perception or contrast detection or anything related to cognition, but he knows it implicitly. It’s an example of the “obviousness” that is human factors design, yet it is definitely not obvious to everyone. Anyway, Read the review here (link goes to start of the UI review portion) – it’s worth your time.