This version is a free update which fixes several bugs, particularly one which produces errors when installing software updates over-the-air for the iPhone 5.
The solution includes a special "iOS updater" app which will be installed for the update, then removed automatically once everything is done.
The full change log has been posted on the Apple website, below is a snippet of the announcement:
Fixes a bug that prevents iPhone 5 from installing software updates wirelessly over the air.
Fixes a bug where horizontal lines may be displayed across the keyboard.
Fixes an issue that could cause camera flash to not go off.
Improves reliability of iPhone 5 and iPod Touch (5th generation) when connected to encrypted WPA2 Wi-Fi networks.
Resolves an issue that prevents iPhone from using the cellular network in some instances.
Consolidated the Use Cellular Data switch for iTunes Match.
Fixes a Passcode Lock bug that sometimes allowed access to Passbook pass details from lock screen.
Fixes a bug affecting Exchange meetings.