The final stable release of version 3.4 is now publicly available for install via the dashboard updates for those already running it or the WordPress website at http://www.wordpress.org
Some of the most significant changes with this version are the introduction of the theme customizer which allows users the opportunity to play around with various looks and settings for your current theme or one you’re thinking about switching to without publishing those changes to the whole world.
According to the release posting, other changes include:
For more details on this release: http://wordpress.org/news/2012/06/green/