New setting mod.SHARED.disableLanguages (available from PageTS) takes a list of languages, and makes them unavailable for part of the page tree.

More info:
RFC #10432: Page TS option to disable avaiable languages
http://bugs.typo3.org/view.php?id=10432

BE can be locked by maintenance. For that a file typo3conf/LOCK_BACKEND needs to be created – either manually, or using the CLI script lowlevel_admin.

CLI scripts will still have access to the system, and could be used for maintenance during that time.

More info:
http://forge.typo3.org/repositories/diff/typo3v4-core?rev=4901
RFC: #10322: Send Notification if BE is locked
http://bugs.typo3.org/view.php?id=10322

List of records can be collapsed by type. The new icons are visible in the List module:

More info:
RFC #2859: Feature: List view should have ‘collapse’ / ‘expand’ functionality for all list types
http://bugs.typo3.org/view.php?id=2859

There are some new functions that load JS libraries:

$this->doc->getPageRenderer()->loadPrototype();
Loads prototype if it wasn’t loaded already
$this->doc->getPageRenderer()->loadScriptaculous();
Loads Scriptaculous, if it wasn’t loaded already
$this->doc->getPageRenderer()->loadScriptaculous('effects,dragdrop');
Loads Scriptaculous with modules
$this->doc->getPageRenderer()->loadExtJS();
Loads ExtJS. This function also accepts two parameters: if first is set to true, ext-all.css will be loaded, if second is set to true, gray theme will be loaded.
If you would like to add ExtJS code to the BE module which has a template class defined (which most BE modules do), you can now add it to an array:
$this->doc->extJsCode[] = …

This code will be inserted into the header section of the page, and wrapped in Ext.onReady(function() { … });

More info:
RFC: #10121: New template-function to add extJS inline code
http://bugs.typo3.org/view.php?id=10121
RFC: #10144: enable JS-Libs in BE
http://bugs.typo3.org/view.php?id=10144

New method in t3lib_db allows easy execution of count SQL statement. For example:

$countPages = $GLOBALS[‘TYPO3_DB’]->exec_SELECTcountRows(‘*’, ‘pages’, ‘deleted = 0’);

More info:
RFC: Feature Request #10091: Integrate TYPO3_DB->exec_SELECTcountRows()
http://bugs.typo3.org/view.php?id=10091