http://support.apple.com/kb/DL1691 This update contains improvements and bug fixes, including:

Adds iCloud Keychain to keep track of your account names, passwords, and credit card numbers across all your approved devices
Adds Password Generator so Safari can suggest unique, hard-to-guess passwords for your online accounts
Updates lock screen to delay display of "slide to unlock" when Touch ID is in use
Adds back the ability to search the web and Wikipedia from Spotlight search
Fixes an issue where iMessage failed to send for some users
Fixes a bug that could prevent iMessage from activating
Improves system stability when using iWork apps
Fixes an accelerometer calibration issue
Addresses an issue that could cause Siri and VoiceOver to use a lower quality voice
Fixes a bug that could allow someone to bypass the Lock screen passcode
Enhances the Reduce Motion setting to minimize both motion and animation
Fixes an issue that could cause VoiceOver input to be too sensitive
Updates the Bold Text setting to also change dial pad text
Fixes an issue that could cause supervised devices to become un-supervised when updating software

Available via iTunes and wirelessly