Arduino - Open-Source Electronics Prototyping Platform

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It's intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments. Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino programming language (based on Wiring) and the Arduino development environment (based on Processing). Arduino projects can be stand-alone or they can communicate with software on running on a computer (e.g. Flash, Processing, MaxMSP). The boards can be assembled by hand or purchased preassembled; the software can be downloaded for free.

Useful Links:
Homepage Arduino Programming Language
Blog Arduino Programming Language
Arduino Programming Language Playground
Arduino Tag on Flickr
Arduino Tag on del.icio.us
Wiring
Processing