Link: WordPress 3.4 Field Guide for Developers

Hey there! I'm currently working on a CLI tool to deploy WordPress apps to DigitalOcean. Check it out! It's free and open source.

A new API for custom headers and backgrounds, flexible headers, live previews (the Theme Customizer), changes around XML-RPC and i18n and l10n. All of this and more in the WordPress 3.4 Field Guide for Developers.