The target application is a very minimalistic PDF organizer and reader which allows users to carry their documents whereever they go. I've attached a screen shot of the current status (pre-release, obviously) of the main UI which features a textured background (leather).
The application design is very iWork-like, so ideally the application icon would fit in the same category as these applications.
The main element of the icon should be a distinct shape which somehow conveys the focus of the application to the user. It should be generic enough (no mention of PDF and no text at all on the icon) so that it allows me to add support for other formats should I decide to do so.
The icon should be made available in the following sizes:
You have full creative control over all aspects of the icon, within the boundaries I established above. If you have reason to believe that you can deliver a top-notch icon only if you break some of these requirements, feel free to give it a try. I'm not an expert on design, but you are. So maybe you know what's best better than I do. :)
Feel free to ask away if you have any questions.