Really great article from pxldot on Mac versus iOS app icons.
The much more interesting icons are those that have focused their design on communicating more clearly by getting rid of, or greatly reducing the visibility of, non-key details. I love this technique in that it mirrors the overall process of transitioning an app from the Mac to the iPhone/ iPad - not every detail can be transferred, and a careful focus on which to highlight can vastly improve the experience by optimizing each device for the subset of features users are most likely to need. I doubt that the icon designers intended to mirror the entire development process in their design, but I like it nonetheless.
(Via Daring Fireball)