Matt Richardson from MAKE provides this introduction to the BeagleBone dev board. BeagleBone is an TI AM3358 ARM Cortex-A8-based microprocessor board that ships with a 2GB microSD card with the Angstrom Linux Distribution with node.js and Cloud9 IDE. It retails for $89 from MAKE and Adafruit.
Here’s another intro to the board by Jason Kridner from TI and a participant in the BeagleBoard.org community. This site contains a wealth of technical information about the board and projects.