UI Guidelines for mobile

Official user interface (UI) and user experience (UX) guidelines from the manufacturers... i hope these links are useful. please feel free to add more links in comments section.

• iPhone Human Interface Guidelines – PDF version
• iPad Human Interface Guidelines – PDF version
• UI Guidelines for BlackBerry 6.0 Smartphones – PDF version
• UI Guidelines for BlackBerry 4.x, 5.x Smartphones – PDF version
• Android User Interface Guidelines
• BlackBerry Browser Content Design Guidelines (PDF)
• Motorola’s Best Practices for Android UI
• Nokia Design & User Experience Library
• Symbian^3 UI Style Guidelines (PDF)
• Forum Nokia Design Portal (PDF)
• Symbian UI Wiki
• Nokia Series 40 UI Style Guide
• Bada Application UI Guide
• Sony Ericsson UI Rulebook
• UI Guidelines for Windows Mobile
• Windows Touch UI Guideline
• UI Design & Interaction Guide for Windows Phone 7 (PDF)
• webOS UI Guidelines
• Hildon UI Guidelines for Nokia Maemo
• MeeGo UI Design Guidelines (shared by Mark Jones)
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  http://meego.com/developers/ui-design-guidelines/handset
   

source http://www.mobilexweb.com/blog/ui-guidelines-mobile-tablet-design