Apple iMac Wi-Fi Update
Fixes a Wi-Fi connection issue on late 2009 or later iMacs.
Developer website: Apple
Apple iMac Wi-Fi Update resolves an issue that may cause an iMac to not automatically connect to a known Wi-Fi network after waking from sleep. It is recommended for all iMac (Late 2009 or newer) users running 10.7.3.
Requirements
OS X 10.7.3 or later