Heads Up To Developers: WordPress 3.4 is in Beta

See the post on the wpdevel site:

 Here’s some of what’s new:

  • 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

And some of the under-the-hood changes:

  • New XML-RPC API for external and mobile applications
  • New API for registering theme support for custom headers and backgrounds
  • Performance improvements to WP_Query by splitting the query (Please test!)
  • Internationalization improvements (improved performance and locale support)
  • Performance and API improvements when working with lists of installed themes
  • Support for installing child themes from the WordPress Themes Directory

Note: there are changes in WordPress 3.4 that will impact Themes, and the Theme Review guidelines. Now is the time to switch your development environments over to the beta version, and start hammering on the changes. (And if you find any bugs, report them!) Soon, the Theme Review Team will begin discussions regarding changes to the Guidelines. If you are interested in participating in those discussions, please beta-test now, and keep your eye on this site, and on the Theme-Reviewers mail-list.