As the author points out, wireless cards for arduino can run you 50-60 dollars. So he not only adapted the TP-link for the arduino, but converted it to fit on the arduino like an arduino shield. Me, thats too much work, I would do the other conversion so I could use it with other systems.
http://hackanerd.wordpress.com/2013/07/06/how-to-make-a-simple-arduino-wireless-shield/