I always thought of the Wii as adopting the "Dashboard" variant of Aqua, which uses gradients rather than stripes and favors a more varied color palette than just white/gray and metal.

(PS: Yep, the same overall tone that is used in the iPhone UI, by the way.)

I find it very interesting (for as long as I own a Wii, which is for as long as Dec. 8), that there are quite a few different channels on the Wii, the settings and the Wii Sports and Wii Play games that are all designed by Nintendo. There seems to be a concept behind all the different design styles, but they simply don't match exactly. When you look on the News channel or Weather channel, they are somewhat connected to the main settings (speaking of button design and that stuff) but they don't look the same. In the beginning, I was a bit annoyed because I thought they just couldn't manage to create a unified look. As time passes, I come to think that Nintendo tries to make the channels distinctable by simply seeing the design, not by reading what's on the buttons and in the text fields. Additionally, by not making every screen look alike, there's less boredom in using the Wii, it becomes more fun.
Now comes the interesting thing: Isn't all that somewhat connected to the intentions behind Disco, Cha-Ching and some interfaces that use CoreAnimation (the few I've seen...)? Make everything be a bit new, a bit exciting to use, a bit different, but still make it look so it fits in the whole design? I do think so and that's funny because Nintendo as a single company and the community of people who develop for Mac OSX (and Apple themselves) seem to come to pretty much the same results in terms of designing interfaces.

The thing about that, Marco, is that with the Wii, you're only looking at one interface at once, while on the Mac you may be running Disco, Cha-Ching, Finder, and iTunes all at once.

Richard, I don't seem to get your point. Yes, on the Wii you only see one application at a time, on Mac OSX you see a lot of applications at any time. As you mention it, Apple themselves are "experts" in look-inconsistency. Undoubtedly, Safari, Mail and iTunes are some of the most used programs on every Mac out there, but they don't look the same. They are quite the same to use, but they are all a bit different in terms of design (here, design == the way the look). And they are on the same screen oftentimes.
Still, the way of making every application look a bit different and all that lets you recognise it a bit better when looking at a random screenshot of a Mac or a Wii.
But imho, it doesn't really matter if there is more than one application on the screen or not (the Disco developers probably didn't design that interface and think it will be used throughout the OSX). The point is still the same.

BTW: how do I leave the URL field in the comments form empty? Just leaving it or entering a space doesn't seem to work...

Apple have perfectly valid reasons for having its applications look different -- it makes them *much* easier to distinguish when using Exposé. Consistency is also about behaviour, not just how things look (i.e. so long as a button looks like a button and acts like all other buttons, it doesn't really matter if it looks slightly different from a button in another app).

how do I leave the URL field in the comments form empty? Just leaving it or entering a space doesn't seem to work

You have to provide either an email address or your site url. You can leave out either one but not both.

Yeah, I used the UNO workaround for several weeks, so all of my applications looked the same way. While working with one interface design I realized that it's easier to have "a lot" of different themes, so I could better recognize the running apps. It is very useful that Firefox, Vienna, Mail and other apps which I use at an everyday basis look different. It makes things a lot easier!

It wouldn't be so nice if Apple would introduce one design in Leopard, but these are just my personal 2 cents.