Firefox 3 Beta 4

After about one month Mozilla rolled out Firefox 3 Beta 4, which includes over 900 additional improvements related to the previous beta release, but it's being made available for testing purposes only.

                                       Firefox 3 beta 4 with new icons on Vista

                                        The Options dialog in Firefox 3 beta 4

                                         The Add-ons dialog in Firefox 3 beta 4

Firefox 3 is based on the new Gecko 1.9 Web rendering platform, which has been under development for the past 31 months and includes nearly 2 million lines of code changes, fixing more than 12,000 issues. Firefox 3 Beta 4 features more than 900 enhancements from the previous beta, including improvements to performance and memory usage, as well as fixes for stability, platform enhancements and user interface improvements.
In this new beta version, several new technologies work together to reduce the amount of memory used by Firefox 3 Beta 4 over a Web browsing session. Memory cycles are broken and collected by an automated cycle collector, a new memory allocator reduces fragmentation, hundreds of leaks have been fixed, and caching strategies have been tuned.
New security enhancements include phishing protection that alerts users when they land on a Web site that is a suspected fake. The browser offers a warning and a redirect to a search page in order to locate the real, desired Web site. In addition, Firefox does not allow a Web site to download, install, or run programs (including spyware) on a computer without the user's explicit agreement. The browser also warns users when they arrive at sites known to download malware, and prevents installation.
The new beta offers hundreds of user-friendly changes, including an improved download manager that streamlines finding downloaded files. Enhancements made to tabbed browsing lets users close tabs independently; if a tab is accidentally closed, a list of recently closed tabs is available under the History menu. Should too many tabs be open to view at once, scroll arrows can be used to access a list of all open tabs.
Firefox 3 Beta 4 is now available for download. This is the twelfth developer milestone focused on testing the core functionality provided by many new features and changes to the platform scheduled for Firefox 3.

Read more about What's New in Firefox 3 on Mozilla.
Read more on ars technica.

* The pictures added in this article are taken from ars technica.