Here's the official word from Mozilla:

Major performance enhancements and revolutionary “Awesome Bar” make Firefox 3 the fastest, smartest, most powerful browser Mozilla has ever released

MOUNTAIN VIEW, CALIF. - June 17, 2008 - Mozilla today released Firefox 3, a major update to its popular and acclaimed free, open source Web browser.  Firefox 3 is the culmination of three years of efforts from thousands of developers, security experts, localization and support communities, and testers from around the globe.

Available today in approximately 50 languages, Firefox 3 is two to three times faster than its predecessor and offers more than 15,000 improvements, including the revolutionary smart location bar, malware protection, and extensive under the hood work to improve the speed and performance of the browser.

“We’re really proud of Firefox 3 and it just shows what a committed, energized global community can do when they work together,” said John Lilly, CEO of Mozilla.

What’s New in Firefox 3:

The Web is all about innovation, and Firefox 3 sets the pace with dozens of new features to deliver a faster, more secure and customizable Web browsing experience for all. 

User Experience.  The enhancements to Firefox 3 provide the best possible browsing experience on the Web. The new Firefox 3 smart location bar, affectionately known as the  “Awesome Bar,” learns as people use it, adapting to user preferences and offering better fitting matches over time. The Firefox 3 Library archives browsing history, bookmarks, and tags, where they can be easily searched and organized. One-click bookmarking and tagging make it easy to remember, search and organize Web sites. The new full-page zoom displays any part of a Web page, up close and readable, in seconds.

Performance. Firefox 3 is built on top of the powerful new Gecko 1.9 platform, resulting in a safer, easier to use and more personal product. Firefox 3 now uses less memory while it’s running, and its redesigned page rendering and layout engine means users see Web pages two to three times faster than Firefox 2. 

Security. Firefox 3 raises the bar for security. The new malware and phishing protection helps protect from viruses, worms, trojans and spyware to keep people safe on the Web. Firefox 3’s one-click site ID information allows users to verify that a site is what it claims to be. Mozilla’s open source process leverages the experience of thousands of security experts around the globe.

Customization. Everyone uses the Web differently, and Firefox 3 lets users customize their browser with more than 5,000 add-ons.  Firefox Add-ons allow users to manage tasks like participating in online auctions, uploading digital photos, seeing the weather forecasts, and listening to music, all from the convenience of the browser. The new Add-ons Manager helps users to find and install add-ons directly from the browser.

For more information about Mozilla Firefox 3 and how it delivers an easier, faster, and safer online experience, visit http://www.mozilla.com/firefox/features.html.

Mozilla Firefox 3 is available now for Windows, Linux, and Mac OS X operating systems as a free download from http://www.getfirefox.com.

The release of Firefox 3 kicks off Download Day, the Mozilla community’s grassroots campaign to set a brand new Guinness World Record for the greatest number of software downloads in 24 hours. The worldwide community effort begins the minute Firefox 3 is released and will continue for a full day.  For more information, please visit http://www.spreadfirefox.com/worldrecord/.

About Mozilla

Mozilla is a global community dedicated to building free, open source products and technologies that improve the online experience for people everywhere. We work in the open with a highly disciplined, transparent and cooperative development process, under the umbrella of the non-profit Mozilla Foundation. As a wholly owned subsidiary, the Mozilla Corporation organizes the development and marketing of Mozilla products. This unique structure has enabled Mozilla to financially support and cultivate competitive, viable community innovation. For more information, visit www.mozilla.com.