The release is not just security, but a few feature fixes as well. Here are the details provided by Andrew Nacin.
- Fixes an issue where a theme’s page templates were sometimes not detected.
- Addresses problems with some category permalink structures.
- Adds early support for uploading images on iOS 6 devices.
- Allows for a technique commonly used by plugins to detect a network-wide activation.
- Better compatibility with servers running certain versions of PHP (5.2.4, 5.4) or with uncommon setups (safe mode, open_basedir), which had caused warnings or in some cases prevented emails from being sent.
Needless to say, update as soon as you can. Happy Pressing :)