This will soon be renamed to Firefox 3.5 as there are a substantial amount of under the hood changes.
Also you can thank me from stopping them from shipping with broken aero animation as I bugged them to hell and back to fix it.
- This beta is now available in 64 languages - get your local version.
- Improved the new Private Browsing Mode.
- Improvements to web worker thread support.
- New native JSON support.
- Improvements to the Gecko layout engine, including speculative parsing for faster content rendering.