New Features

    *  Tabs are now on top by default on Windows only - OSX and Linux will be changing when the theme has been modified to support the change.
    * On Windows Vista and Windows 7 the menu bar has been replaced with the Firefox button.
    * You can search for and switch to already open tabs in the Smart Location Bar
    * New Addons Manager and extension management API (UI will be changed before final release)
    * Significant API improvements are available for JS-ctypes, a foreign function interface for extensions.
    * The stop and reload buttons have been merged into a single button on Windows, Mac and Linux.
    * The Bookmarks Toolbar has been replaced with a Bookmarks Button by default (you can switch it back if you'd like).
    * Crash protection for Windows, Linux, and Mac when there is a crash in the Adobe Flash, Apple Quicktime or Microsoft Silverlight plugins.
    * CSS Transitions are partially supported.
    * Full WebGL support is included but disabled by default at this time.
    * Core Animation rendering model for plugins on Mac OS X. Plugins which also support this rendering model can now draw faster and more efficiently.
    * Native support for the HD HTML5 WebM video format.
    * An experimental Direct2D rendering backend is available on Windows, turned off by default.
    * Web developers can use Websockets for a low complexity, low latency, bidirectional communications API.
    * Web developers can update the URL field without reloading the page using HTML History APIs.
    * More responsive page rendering using lazy frame construction.
    * Link history lookup is done asynchronously to provide better responsiveness during pageload.
    * CSS :visited selectors have been changed to block websites from being able to check a user's browsing history.
    * New HTML5 parser.
    * Support for more HTML5 form controls.


Haven't tried this out yet but might give it a go later on.

Windows Download
OS X Download
Linux Download

Release Notes