Apple has released an update for all "late 2012" Macs which improves compatibility when using the 5GHz band in Wi-Fi. The update weighs in at a tiny 1.49 MB and requires OS X 10.8.2. Users can download it via Software Update or the link below.
This update is recommended for all late 2012 Mac systems. This update improves compatibility when using the 5GHz band in Wi-Fi.
Boot ROM or SMC Version Information: To confirm the update has been applied, the CFBundleVersion string of the AirPortBrcm4311.kext will need to be checked.
New driver delivered in update: AirPortBrcm4331.kext CFBundleVersion = 612.20.15/System/Library/Extensions/IO80211Family.kext/Contents/PlugIns/AirPortBrcm4331.kext/Contents/Info.plist