The first Firefox 3 Release Candidate is now available for download. This milestone is focused on testing the core functionality provided by many new features and changes to the platform scheduled for Firefox 3. Ongoing planning for Firefox 3 can be followed at the Firefox 3 Planning Center, as well as in mozilla.dev.planning and on irc.mozilla.org in #granparadiso.

New features and changes in this milestone:

* Improvements to the user interface based on user feedback, including changes to the look and feel on Windows Vista, Windows XP, Mac OS X and Linux.

* Changes and fixes for new features such as the location bar autocomplete, bookmark backup and restore, full page zoom, and others, based on feedback from our community.

* Fixes and improvements to platform features to improve security, web compatibility and stability.

* Continued performance improvements: changes to our JavaScript engine as well as profile guided optimization continues to improve performance over previous releases as measured by the popular SunSpider test from Apple, and in the speed of web applications like Google Mail and Zoho Office.

More Here