Buttons are a good example of skeuomorphic done right. In real life, if something's supposed to be turned, I expect it to be a knob. If something's going to be pulled, I expect there to be a handle. Since you're expected to click or tap buttons, it they should obviously look like buttons.
I think that Apple's decision to continue buttonizing touch UI was probably wise in the beginning, but seeing Windows Phone 7's all flat everything approach feels really fresh. Why don't they chrome up their touchable objects? Because its a _touch screen_ and the only thing you can POSSIBLY do is _touch_ them. The context is I took out my device to do something with it, I expect to be touching things.
So while buttons may still need to be buttons on the desktop, I'm happy to see chrome fade away in touch UIs.