Add new admin theme with color variations. The new admin theme is located in /site-default/templates-admin/. See /site-default/templates-admin/README.txt for more information. Note that this theme needs testing, so stick to the old admin theme if you don't want to help test.
Add Adamspruijt's LanguageFieldTabs module to core. Renamed to LanguageTabs, in case you've already got LanguageFieldTabs installed. The core version has also been updated for compatibility with the new admin theme included on dev.