Rogue Amoeba's The Delicious Generation post is one of many commenting on the rise of "shiny thing" applications (where the primary selling point appears to be graphics) on OSX - the latest of which is Disco.

On one hand, I agree that these apps sometimes sacrifice usability to add graphical dirt. On the other hand, I think some of the things they're doing are really good and are pushing towards where the UI is heading - such as a greater use of animation. If it's ok for Apple to use animation in FrontRow or iTunes, why shouldn't Disco?

I think the source of these new UI styles is that Apple and the other UI toolkit providers are still stuck in the 1980s. In over 20 years, almost nothing has changed aside from fancier textures on the widgets. Real improvements are long overdue.

For what it's worth, here are some of my guesses as to where UIs are headed:

Spartan

Functional widgets will loose their decoration and become simple rounded rectangles. Disco did a great job with this and you can see this trend in the xbox 360 and other UIs. Richness belongs in the picture, not the frame.

Animated

Animation will be used to replace the current magic popping in and out of existence or windows, views, panels, etc with continuous and connected animations that make ithe relationships between things clearer.

Text as a UI

Text as a user interface will become increasingly common - we "get" the idea that clicking on text can do something and we no longer need it to be blue or underlined or to be in something that looks 3d or anything like conventional UI widgets. Examples: may web UIs, the Safari bookmarks bar.

Custom Views

As programming tools and UI frameworks get better, I think developers will stop trying to fit the square peg of the current widget sets into their problem domains, at least when it comes to interacting with application specific information.

Unified Navigation

UIs are primarily about navigating some graph of information. We'll develop some common ways of presenting this information and animating it's navigation. Perhaps using the iPod's navigation style, for example.