代號為Gran Paradiso 的Firefox 3最重要的功能就是整合性的瀏覽歷史、書籤功能Places，也就是Bookmarks on Places。另外，更新的瀏覽器引擎Gecko有更好的效能表現。另外還有續傳下載管理器、整頁縮放、遠端資料夾功能、支援OpenID與微格式(microformats)等等，microformats本站也有支援，可以看到簡單的連絡人資訊。
有興趣的用戶可以下載不同跨平台與語言版本的Firefox 3 Beta 2測試，雖然已經有多國語文版本出爐，有簡體中文，可是官方正式開放的公開測試版2，其繁體中文仍舊是暫時沒有。XD
[Improved in Beta 2!] Firefox 3 Beta 2 includes approximately 900 improvements over the previous beta, including fixes for stability, performance, memory usage, platform enhancements and user interface improvements. Many of these improvements were based on community feedback from the previous beta.
* One-click site info: Click the site favicon in the location bar to see who owns the site. Identity verification is prominently displayed and easier to understand. In later versions, Extended Validation SSL certificate information will be displayed.
* Malware Protection: malware protection warns users when they arrive at sites which are known to install viruses, spyware, trojans or other malware. You can test it here (note: our blacklist of malware sites is not yet activated).
* New Web Forgery Protection page: the content of pages suspected as web forgeries is no longer shown. You can test it here.
* New SSL error pages: clearer and stricter error pages are used when Firefox encounters an invalid SSL certificate.
* Add-ons and Plugin version check: Firefox now automatically checks add-on and plugin versions and will disable older, insecure versions.
* Secure add-on updates: to improve add-on update security, add-ons that provide updates in an insecure manner will be disabled.
* Anti-virus integration: Firefox will inform anti-virus software when downloading executables.
* Vista Parental Controls: Firefox now respects the Vista system-wide parental control setting for disabling file downloads.
* [Improved in Beta 2!] Effective top-level domain (eTLD) service better restricts cookies and other restricted content to a single domain.
* [Improved in Beta 2!] Better protection against cross-site JSON data leaks.
Easier to Use
* Easier password management: an information bar replaces the old password dialog so you can now save passwords after a successful login.
* Simplified add-on installation: the add-ons whitelist has been removed making it possible to install extensions from third-party sites in fewer clicks.
* [Improved in Beta 2!] New Download Manager: the revised download manager makes it much easier to locate downloaded files, and displays where a file came from.
* Resumable downloading: users can now resume downloads after restarting the browser or resetting your network connection.
* Full page zoom: from the View menu and via keyboard shortcuts, the new zooming feature lets you zoom in and out of entire pages, scaling the layout, text and images.
* Tab scrolling and quickmenu: tabs are easier to locate with the new tab scrolling and tab quickmenu.
* Save what you were doing: Firefox will prompt users to save tabs on exit.
* Optimized Open in Tabs behavior: opening a folder of bookmarks in tabs now appends the new tabs rather than overwriting.
* Location and Search bar size can now be customized with a simple resizer item.
* Text selection improvements: multiple text selections can be made with Ctrl/Cmd; double-click drag selects in "word-by-word" mode; triple-clicking selects a paragraph.
* Find toolbar: the Find toolbar now opens with the current selection.
* Plugin management: users can disable individual plugins in the Add-on Manager.
* Integration with Vista: Firefox's menus now display using Vista's native theme.
* Integration with the Mac: Firefox now uses the OS X spellchecker and supports Growl for notifications of completed downloads and available updates.
* [Improved in Beta 2!] Integration with Linux: Firefox's default icons, buttons, and menu styles now use the native GTK theme.
* Star button: quickly add bookmarks from the location bar with a single click; a second click lets you file and tag them.
* Tags: associate keywords with your bookmarks to sort them by topic.
* [Improved in Beta 2!] Location bar & auto-complete: type in all or part of the title, tag or address of a page to see a list of matches from your history and bookmarks; a new display makes it easier to scan through the matching results and find that page you're looking for.
* [Improved in Beta 2!] Smart Bookmarks Folder: quickly access your recently bookmarked and tagged pages, as well as your more frequently visited pages with the new smart bookmarks folder on your bookmark toolbar.
* [Improved in Beta 2!] Places Organizer: view, organize and search through all of your bookmarks, tags, and browsing history with multiple views and smart folders to store your frequent searches.
* [Improved in Beta 2!] Web-based protocol handlers: web applications, such as your favorite webmail provider, can now be used instead of desktop applications for handling mailto: links from other sites. Similar support is available for other protocols (Web applications will have to first enable this by registering as handlers with Firefox).
* Easy to use Download Actions: a new Applications preferences pane provides a better UI for configuring handlers for various file types and protocol schemes.
Improved Platform for Developers
* New graphics and font handling: new graphics and text rendering architectures in Gecko 1.9 provides rendering improvements in CSS, SVG as well as improved display of fonts with ligatures and complex scripts.
* Native Web page forms: HTML forms on Web pages now have a native look and feel on Mac OS X and Linux (Gnome) desktops.
* Color management: (set gfx.color_management.enabled on in about:config and restart the browser to enable.) Firefox can now adjust images with embedded color profiles.
* Offline support: enables web applications to provide offline functionality (website authors must add support for offline browsing to their site for this feature to be available to users).
* A more complete overview of Firefox 3 for developers is available for website and add-on developers.
* Reliability: A user's bookmarks, history, cookies, and preferences are now stored in a transactionally secure database format which will prevent data loss even if their system crashes.
* [Improved in Beta 2!] Speed: Major architectural changes (such as the move to Cairo and a rewrite to how reflowing a page layout works) put foundations in place for major performance tuning which have resulted in speed increases in Beta 2, and will show further gains in future Beta releases.
* [Improved in Beta 2!] Memory usage: Over 300 individual memory leaks have been plugged, and a new XPCOM cycle collector completely eliminates many more. Developers are continuing to work on optimizing memory use (by releasing cached objects more quickly) and reducing fragmentation. Beta 2 includes over 30 more memory leak fixes, and 11 improvements to our memory footprint.