The official user interface (UI) and user experience (UX) guidelines from the manufacturers, links to which you can find below, are a source of inspiration for mobile web and application design. Here, you will find guidelines, samples, tips, and descriptions of common mistakes. Many of the guidelines focus on native application development, but we can apply most parts of them to mobile web design.
Apple (iOS)
- iOS Human Interface Guidelines or the PDF version (PDF 12.9MB, pp. 150)
Google (Android)
Microsoft (Windows Mobile, Windows Phone 7)
- UI Guidelines for Windows Mobile
- Windows Touch UI Guideline
- UI Design & Interaction Guide for Windows Phone 7 version 2.0 (PDF 11.9MB, pp. 101)
via Simon Whatley – User Interface Guidelines for Mobile and Tablet Devices.