Join me Sunday April 12th for the Boston Arduino Meetup (I am the organizer)! For more information: Arduino 101: Wireless Communication with NRF24L01 and door alarms. We'll be at the Microsoft NERD Center in Cambridge.
From Wikipedia: Arduino is a single-board microcontroller to make using electronics in multidisciplinary projects more accessible. The hardware consists of an open-source hardware board designed around an 8-bit Atmel AVR microcontroller, or a 32-bit Atmel ARM. The software consists of a standard programming language compiler and a boot loader that executes on the microcontroller.