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 1.26wmf12 (f0490d8), 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.
The back-end code for the MediaWiki preferences system was recently upgraded. As with many major upgrades, this caused a number of bugs. The "Enable e-mail from other users" feature in the preferences was broken in that when selected and checked from the preferences, then browsed away from the page, and then came back, the option was shown as unchecked. This bug has been resolved. (r49919, bug 18581) Also, the "e-mail confirmation date" and button for receiving a new e-mail confirmation were missing in the user preferences. These have been re-added. (r49920, bug 18580)
For a period of time, non-admins were unable to view page protection settings by attaching "action=protect"; This ability has been restored for non-admins. (r50420, bug 18728)
The change tagging feature has been enabled on the Abuse filter. Filters can be added on Special:Tags for identifying edits that blank pages, remove references, or other such actions that merit extra scrutiny. These tagged edits can be filtered on recent changes, and will appear on user watchlists with an added edit summary. 
Major changes are currently being implemented to improve the search interface, in response to work by the usability project team. The new interface will allow searching main/article space by default, along with a media/image search option, help pages (Help and Wikipedia namespaces) search, an option to search everything, and an advanced search option which allows users to choose which namespaces to search. (r50207)
IP block exemptions are now enabled on all Wikimedia wikis, allowing exemptions from tor blocks and other range blocks. (bug 18337)