The newly released Arduino Leonardo has a few very interesting features, most notably the ability to act as a USB keyboard and mouse ... to have your old Arduino board gain some of the features ...

It's like a shrunken version of the Arduino Leonardo as it features the same ATmega32U4 microcontroller, micro-USB port ... double as analog input pins on both boards. That's where the ...

USB is not a native feature on all microcontrollers or even Arduino-compatible boards. While some do have it built in like those based on the 32u4 for example, most either don’t have it at all ...