Afinal ainda não saiu a versão final mas sim mais uma RC3:

Here's what's new in Firefox 1.5 RC 3:

# Automated update to streamline product upgrades. Notification of an update is more prominent, and updates to Firefox may now be half a megabyte or smaller. Updating extensions has also improved.
# Faster browser navigation with improvements to back and forward button performance.
# Drag and drop reordering for browser tabs.
# Improvements to popup blocking.
# Clear Private Data feature provides an easy way to quickly remove personal data through a menu item or keyboard shortcut.
# Answers.com is added to the search engine list.
# Improvements to product usability including descriptive error pages, redesigned options menu, RSS discovery, and "Safe Mode" experience.
# Better accessibility including support for DHTML accessibility and assistive technologies such as the Window-Eyes 5.5 beta screen reader for Microsoft Windows. Screen readers read aloud all available information in applications and documents or show the information on a Braille display, enabling blind and visually impaired users to use equivalent software functionality as their sighted peers.
# Report a broken Web site wizard to report Web sites that are not working in Firefox.
# Better support for Mac OS X (10.2 and greater) including profile migration from Safari and Mac Internet Explorer.
# New support for Web Standards including SVG, CSS 2 and CSS 3, and JavaScript 1.6.
# Many security enhancements.
# List of notable bug fixes since Firefox 1.5 Beta 2

O link:
http://www.mozilla.org/projects/firefox/