[Charles Gantt] and a few others were having trouble burning the Sanguino bootloader to an ATmega644 chip. With some help from the [Nils Vogil] via the RepRap IRC [Charles] got it worked out and wrote ...

The Arduino IDE provides access to these through a function in tools called ‘Burn bootloader’ (available in the Tools menu). In proper Arduinos, this sets appropriate non-volatile flags and downloads ...

Wouldn’t it be great is you could also use the ’16u2 on the Uno or Mega for some additional functionality to your Arduino sketch? That’s now a reality.

The new Arduino prototyping kit allows you to build and program your own circuits using the fully functional and production-ready Arduino prototyping board.