It's the new MEGA 2560 R3. The Arduino MEGA USB board is compatible with most shields for the Duemilanove/Uno and has more pins, UART etc. It sports the bigger Atmega2560 compared to the previous Mega1280.
Our Code: MCU-60065
Supplier Link: [SparkFun MPN:DEV-11061]
The Arduino Mega R3 is a microcontroller board based on the ATmega2560. It has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Mega is compatible with most shields designed for the Arduino Duemilanove or Diecimila.
The Mega 2560 R3 also adds SDA and SCL pins next to the AREF. In addition, there are two new pins placed near the RESET pin. One is the IOREF that allow the shields to adapt to the voltage provided from the board. The other is a not connected and is reserved for future purposes. The Mega 2560 R3 works with all existing shields but can adapt to new shields which use these additional pins.
This is the new Arduino Mega 2560. In addition to all the features of the previous board, the Mega 2560 now uses an ATmega8U2 instead of the FTDI chip. This allows for faster transfer rates, no drivers needed for Linux or Mac (inf file for Windows is needed), and the ability to have the board show up as a keyboard, mouse, joystick, etc. It also has twice as much flash memory.