The single coolest feature—at least from a purely technical standpoint—of the last major version of Mac OS X was Quartz Extreme. When I first installed Jaguar, graphics operations were noticeably speedier, and it was nice to know that much of the work was being done by the graphics card, not by the CPU. Then I discovered screen zooming (find it under “Universal Access” in system preferences). It’s a breathtaking effect. I often use it during demos when giving a talk, because other windows on the screen use smaller fonts than PowerPoint, so it helps the audience if I can zoom in on them. I nearly always hear some under-the-breath reaction from someone in the audience when I first zoom in.

It was immediately clear that screen zooming was achieved by exploiting Quartz Extreme. The fact that the entire desktop is now an OpenGL scene, with each window an OpenGL object, makes the effect both easy-to-implement and fast. James Davidson and I immediately began wondering when Apple would begin using that underlying tech to do other neat things with the desktop.

We didn’t have to wait long. Yesterday Apple showed some previews of Panther, and there are two features that exploit the power of Quartz Extreme to good effect.

The first is Exposé, which I described to a friend as “the Win2K ‘Show Desktop’ button, minus the ‘sucks.’” Try out the demo on the webpage, and you’ll see windows smoothly receding from view until all of the windows on the screen are visible, and then zooming back to normal size again.

The second is Fast User Switching. When you choose to switch to another user’s account, your entire desktop switches over to the new user’s desktop using a “rotating cube” transition (á la Keynote).

On the website, Apple introduces that effect by saying, “Because we can.” In user interfaces, at least, a little of that attitude goes a long way—but I think this is a great place for it. Dazzling effects like that would be distracting and annoying in most parts of the interface, but both of these events—stopping to look for a new window, and switching users—are inherently disruptive events, and they’re great places for Apple to show off a bit. Architecture isn’t everything, but it does matter, and nobody knows that better than Apple (who labored under the burden of a terrible OS architecture for years). Of course, the OS X architecture isn’t perfect, but starting from a mostly clean slate is a big advantage, and now that they’ve pulled the switch off I’m sure they’re gleeful.

Be careful with the desktop experience, Apple—but keep having fun. It’s one of the things we like about you.