Apple has posted Mac Wi-Fi Update 1.0 for Mac OS X 10.8.2 or higher.
Apple says the update is recommended for all late 2012 Mac systems. This update improves compatibility when using the 5GHz band in Wi-Fi.
To confirm the update has been applied, the CFBundleVersion string of the AirPortBrcm4311.kext will need to be checked. You can learn more at http://support.apple.com/kb/DL1620?viewlocale=en_US&locale=en_US .