A new version of the Single User Login system for global accounts will be enabled on July 17. Users will now automatically go back to the previous page instead of seeing the "Login success" page with logos. 
The software that resizes images on all wikis will change on July 18. Resizing of big images will be faster and more reliable, and the resolution limit for GIF, PNG and TIFF files (currently set at 50 megapixels) will be removed. 
Edit tags (mostly used by AbuseFilter) will now also be on diff pages. They include a link to Special:Tags before the edit summary. Wikis that use links in tag messages should remove them. 
Global edit filters are currently in testing and will be added to wikis later.