WordPress 3.4 Beta 3 is now available for download.what’s new in this beta?
Nearly 90 changes.
all of the fixes included in version 3.3.2.
Some new features in 3.4
Theme Customizer with Previewer
Flexible Custom Header Sizes
Selecting Custom Header and Background Images from Media Library
Better experience searching for and choosing a theme
Download WordPress 3.4 Beta 3