How to send an email with Arduino and a WiFi shield?

What is the required material for controlling an Arduino over Wi-Fi?

• What do you need? I heard that you need the arduino internet shield. Is there an alternative? What is the required material? And, if you were to send data from your iPhone, how would you do it? I want the arduino to be running on a battery, without any connections to the computer, and be able to receive data from the iPhone over wifi telling it to turn on and off.

• Answer:

  You can get a Wifi shield for an Arduino, or you can try to connect an Arduino directly to a device that has Wifi, like this: http://todbot.com/blog/2010/12/16/wifi-for-arduino-with-asus-wl-520gu/ Alternately, you can look into XBee RF modules, one which would be connected to an (always on) computer, and one that would be connected to your Arduino.