Currently I am using a MacBook Pro with OS X 10.8.5 and I just noticed that there is no Wi-Fi option on this machine.
To try to add Wi-Fi to the menu bar, I went to System Preferences → Network and clicked the "+" button from the left list, and in the interfaces section I found nothing named Wi-Fi!
I also tried to search for "wifi" in Spotlight, but there is nothing named like that.
I'm wondering if somehow the software is not installed in this machine. I don't know whether this software comes with the OS X installation or not.