I have tried to get wifi to work on my beaglebone black with limited success, including using the Adafruit instructions. However there is an alternative to a usb wifi that I want to introduce here. There are specialized wifi devices called a wifi AP/Client Router that are used typically to extend the range of wifi. The wifi client device looks and can behave just like a standard wifi router except that they come pre-configured with wifi client software enabled and in a wifi client default state. The device I am using is a TP-LINK model TL-WR743ND (150Mbps Wireless AP/Client Router). What this device does is act as a wifi intermediary between the house wifi router and the beaglebone. After a simple configuration of the wifi client router with the SSID and password (I use WPA2 on my home wifi router), one only needs to connect the standard RJ45 hardwire ethernet cable from your beaglebone into the back of the wireless client router and you have magically created a wifi ‘zone’ that can act as a bridge for other hardwired and wifi devices in the vicinity of the client wireless device. The wifi client device is a little more expensive (under $40) than a usb wifi device but adds much more functionality and flexibility.