Various core-level optimizations and updates including standardization of wire() functions, support for short syntax with hooks (including use of closures in PHP 5.3+), more validation to FieldtypePage, and some refactoring in preparation for additional updates over the coming weeks.
Update the system-wide $this->message() and $this->error() functions to accept a second argument of boolean "true". When specified, like $this->message("my message", true); the message or error will be logged to the appropriate file in /site/assets/logs/.
Improvements to ProcessWire's debug mode output in the default admin theme, including a nice new Hooks section.