Update: Firefox 24 released.

[HansV]

You can get the new version from the built-in update mechanism or from this link.

New/improved:
- Support for new scrollbar style in Mac OS X 10.7 and newer.
- Implemented "Close tabs to the right" (a new right-click option for browser tabs).
- Social: Ability to tear-off chat windows to view separately by simply dragging them out.