For those curious about the ESP8266, it's a 5$ Chinese wifi module which initially had limited/no English documentation. But now people are working on translating and testing the module[1]. Alternatives based on the TI chip from Adafruit and Sparkfun, for example, are about 35$ (with the chip by itself costing around 15$).
You can get modules even cheaper than $5 on certain sites, I think mine cost around $3 from Taobao, which makes it very tempting (the chip itself is even cheaper still).