This is a summary of recent technology and site configuration changes that affect the English Wikipedia. Please note that some bug fixes or new features described below have not yet gone live as of press time; the English Wikipedia is currently running version 1.25wmf18 (b88e25f), and changes to the software with a version number higher than that will not yet be active. Configuration changes and changes to interface messages, however, become active immediately.
3 bots or bot tasks were approved for operation this week. These were:
Improvements have been made on handling Chinese multi-character search terms. (r52338, bug 8445) 
A new system for localisation caching of core and extension messages has been introduced, which involves fetching individual messages. The $wgCacheDirectory variable has been added, replacing $wgFileCacheDirectory, $wgLocalMessageCache and other local caches, and $wgLocalisationCacheConf replaces $wgEnableSerializedMessages and $wgCheckSerialized. (r52503)
The Special:Version page has been updated to show the Math rendering engine version number (r52525), version of the SVG image thumbnailing engine used (r52516), and version of the diff/diff3 engine. (r52486, bug 14611)
Site copyright and TOS statements can now override the default, with messages available. New messages include wikimedia-copyright (page footer), wikimedia-copyrightwarning (edit page, above summary/save button), wikimedia-editpage-tos-summary (edit page, below summary/save button). Defaults for English Wikipedia come from meta:Licensing update/Implementation.
The Wikimedia Foundation blog and the Wikimedia Technical Blog were out of service for the past few days. These were located on a separate server, which had the WordPress installations compromised. The Open Conference Systems site for Wikimania 2009 was also down. The server has been hardened to better protect it in the future. 
GeSHi (Generic Syntax Highlighter) has been updated on Wikimedia sites to the latest version — 188.8.131.52. GeSHi is used to provide syntax highlighting for source code samples. (bug 10967)