Ahh...the classic Arduino.
Arduino is an open-source physical computing platform based on a simple i/o board and a development environment that implements the Processing/Wiring language. Arduino can be used to develop stand-alone interactive objects or can be connected to software on your computer (e.g. Flash, Processing, MaxMSP). The open-source IDE can be downloaded for free (currently for Mac OS X, Windows, and Linux).
This is the new Arduino Duemilanove. The Duemilanove automatically selects the appropriate power supply (USB or external power). A great description of the new functionality can be found here (USB fuse protection, software reset, and much more!). Board comes fully assembled and tested with ATMega328 pre-loaded with bootloader. Please see the Arduino support forum for more information about this new board revision and bootloader.
When your project is ready to move off the bench, you can quickly bolt it into an Chameleon 1 enclosure. There's already a metal faceplate for the Arduino as well as pre-center-punched baseplate hole patterns which make tucking your Arduino and all its project electronics into a hard shell a breeze.
Here's an Arduino in a Chameleon 1 enclosure

The Chameleon 1 is sold separately and works with numerous other dev boards besides Arduino.
Shipped from the USA.
Documents
Arduino Home Page
Duemilanove Features
How To
Programming Reference
Arduino Forum