I find it interesting that Aristo's examples are almost 100% identical to Apple's controls, albeit with less shininess (a good quality in a generic UI, I prefer cleaner). Care to comment on that? (I haven't read the Aristo psd, but cappuccino looks interesting)
And I personally despise those little rotary controls. You can't control them precisely or read them accurately. They're useful only for extremely coarse controls, which few programs have a use for.
The circular slider is a pretty specific user element. Maybe so specific that it doesn't belong in a general purpose framework, I don't know. But it definitely has its place. It's usually coupled with a text field for precision, but it's generally a good tool for setting an angle in a UI.
And I personally despise those little rotary controls. You can't control them precisely or read them accurately. They're useful only for extremely coarse controls, which few programs have a use for.