The first beta version of the second most popular browser's third iteration is freely available for download from Mozilla. While this is not a nightly build, the software is not recommended for casual users until a more mature version is available. Which is to say that the only reason for you to want to take Firefox 3 for a test drive is pure curiosity.

What's new (from the official announcement):

• Improved security features such as: better presentation of website identity and security, malware protection, stricter SSL error pages, anti-virus integration in the download manager, and version checking for insecure plugins.
• Improved ease of use through: better password management, easier add-on installation, new download manager with resumable downloading, full page zoom, animated tab strip, and better integration with Windows Vista and Mac OS X.
• Richer personalization through: one-click bookmarking, smart search bookmark folders, direct typing in location bar searches your history and bookmarks for URLs and page titles, ability to register web applications as protocol handlers, and better customization of download actions for file types.
• Improved platform features such as: new graphics and font rendering architecture, major changes to the HTML rendering engine to provide better CSS, float-, and table layout support, native web page form controls, colour profile management, and offline application support.
• Performance improvements such as: better data reliability for user profiles, architectural improvements to speed up page rendering, over 300 memory leak fixes, and a new XPCOM cycle collector to reduce entire classes of leaks.

Excited yet?