Apple has released OS X Mountain Lion 10.8.1, and the update is now available in the Mac App Store under the Updates tab. A manual installer is also available for download.
In the support notes about the update, Apple recommends backing up your system before running the installer. A reboot is required in order to complete the update.
The update includes a number of fixes:
- Resolve an issue that may cause Migration Assistant to unexpectedly quit
- Improve compatibility when connecting to a Microsoft Exchange server in Mail
- Address an issue playing audio through a Thunderbolt display
- Resolve an issue that could prevent iMessages from being sent
- Address an issue that could cause the system to become unresponsive when using Pinyin input
- Resolve an issue when connecting to SMB servers with long names
- Address a issue that may prevent Safari from launching when using a Proxy Automatic Configuration (PAC) file
- Improve 802.1X authentication with Active Directory credentials