This update includes general operating system fixes that improve the stability and compatibility of your Mac, including fixes that:
- 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.
For information on the security content of this update, please visit: http://support.apple.com/kb/HT1222.
I updated no issues at all and no need to replace any kexts. it was 7.28MB for me.