Firefox 3.6.4 has been in the talks lately because of the intention of the Mozilla developers to add out-of-process plugins to that version of the web browser which basically means that popular plugins run in their own process instead of the main browser process. This is beneficial in case of a plugin crash as it will only take down its own process and not the whole web browser.
The feature was first introduced in the development release Firefox 3.6.3 Plugin 1 and has been carried over to the first beta release of Firefox 3.6.4.
The major feature of the beta is the out-of-process functionality. But the new version fixes several security and stability issues in Firefox 3.6.3 as well.

Firefox users running an earlier version of the Firefox 3.6.x branch might consider switching to the beta release because of the security issues that have been fixed. Bugzilla reports a total of 163 bugs that have been fixed in Firefox 3.6.4 Beta of which 2 have been rated as blockers and 13 as critical.
Many of the issues that have been fixed seem to be related to plugins and the new out-of-process plugins functionality. Interested Firefox users can take a look at the release notes for the full picture which also point to a download of Firefo 3.6.4 Beta.
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Can you post a download link for the latest build, v3.6.4 beta1? Could not find it on the Mozilla’s servers at all. Tnx.
I have received it through a browser update, could not find it either. Maybe you need to download the previous release and check for updates.
how do you tell firefox to download beta version??
I have downloaded this release first: ftp://ftp.mozilla.org/pub/firefox/releases/3.6.3plugin1/ and the update was offered automatically once it was released.
It’s nice to see this improvment. There have been many times that my browser has crashed on Linux because of buggy flash plugin.
For all of you who want to download firefox 3.6.4 Officially, its a beta version so it will not be found on the stable downloads page it is on mozilla’s beta page :http://www.mozilla.com/en-US/firefox/all-beta.html
enjoy.
another thing when checking for updates via firefox, firefox will not notify you about beta downloads you will have to google those yourself, ONLY stable versions that appear on mozilla’s main server will be available for download via firefox’s update check.