Apple has released Mac OS X Mountain Lion 10.8.4 featuring several improvements.

What's New In This Version:
The
10.8.4 update is recommended for all OS X Mountain Lion users and has
features and fixes that improve the stability, compatibility, and
security of your Mac, including the following:
● Compatibility improvements when connecting to certain enterprise Wi-Fi networks
● Microsoft Exchange compatibility improvements in Calendar
● A fix for an issue that prevented FaceTime calls to non-U.S. phone numbers
● A fix for an issue that may prevent scheduled sleep after using Boot Camp
● Improved VoiceOver compatibility with text in PDF documents
● Includes Safari 6.0.5

For detailed information about this update, please visit:
http://support.apple.com/kb/HT5730

For detailed information about the security content of this update, please visit:
http://support.apple.com/kb/HT1222

You can download the OS X 10.8.4 update by selected Software Update from the Apple menu at top left of your screen.