We have provided some useful resources on the Arduino hardware and software that you can use to explore this open source technology:
Official Arduino homepage: http://www.arduino.cc/
Official Arduino forum: http://arduino.cc/forum/
Official Arduino store: http://store.arduino.cc/
Arduino IDE downloads: http://arduino.cc/en/Main/Software
Arduino hardware: http://arduino.cc/en/Main/Products?from=Main.Hardware
Makezine's Arduino blog: http://blog.makezine.com/arduino/