"Latest version of the official blackberry OS "version 4.6" for most newer Blackberry models like the Bold 9000 Meteor and the 9500 Thunder
New features in 4.6 include
Richer BlackBerry Browser Rendering

• –AJAX
  –JavaScript 1.5
  –CSS 2.1
  –DOM L2 (including Core, HTML, Style, Events)
  –HTML 4.01 (including Forms, Maps, Tables, Frames, Objects)
  –XMLHttpRequest
  • Integrated Go To, Search, Bookmarks, and History Launch Screen
  • Easy Zooming
  • Pointer Controls
  • Optimized Page Layout
  • Quality Fonts

• Scrolling Down with the Trackball
• Click Trackball to Zoom In, Click in to Further Zoom in
• BlackBerry Device Software 4.6 includes :
  •Music Sync - a synchronization application for selecting and transferring music from a computer to a BlackBerry smartphone
  •Clock application – the evolution of the alarm application
  •Setup Wizard 2.0 – a new look and improved features
  •Support for grayscale and reverse contrast display
  •Option to select Home screen grid size
  •Support for continuous spell checking
  •Numerous enhancements to existing BlackBerry smartphone applications and features" Read more here: