[Update: Sorry for the confusion, but the Mac version of Firefox does not have the feature that protects against crashes in plug-ins. -Adam]
Mozilla’s Firefox 3.6.6 is a quick update to the just-released 3.6.4, which addressed a handful of security vulnerabilities and improved stability when plug-ins crash. Most notably, if the Flash, QuickTime, or Silverlight plug-ins crash, they won’t take down Firefox itself. (Just reload the page to restart the plug-in.) The security vulnerabilities could result in arbitrary code execution, as usual, so it’s nice to seem them fixed. Release notes are available. Firefox 3.6.6 merely increases the amount of time a plug-in can be non-responsive before it’s terminated. (Free, 19 MB)
Please note that the plug-in crash protection does not exist for the Mac version of Firefox. From the Firefox 3.6.4 release notes:
"Firefox 3.6.4 provides uninterrupted browsing for Windows and Linux users when there is a crash in the Adobe Flash, Apple Quicktime or Microsoft Silverlight plugins."
And from https://wiki.mozilla.org/Firefox/Crash_Protection:
"Why is there no support for Firefox with crash protection on Mac OS X? When will it be available?
The technology used for crash protection requires major changes to Firefox on Mac OS X, and so we are unable to provide this feature to users on that operating system at this time. Crash protection will be available for Mac OS X in Firefox 4."
Firefox 3.6.4 contains many other security fixes that do apply to the Mac. However, Firefox 3.6.6 only fixes the plug-in crash protection, so apparently 3.6.6 contains NO Mac fixes and exists only to keep the version numbers in sync (or else the v. 3.6.6 release notes are incomplete).
Doh! We were obviously moving too quickly and missed that in the release notes. Thanks for the clarification - I'll update the articles with a note.