It’s a significant update. The Arduino UNO and Arduino Mega 2560 update the Duemilanove and Mega respectively. They now use an ATMega8U2 instead of an FTDI USB to serial converter chip.

[Stephane] begs to differ, and coded this Bad Apple!! demo for the Arduino Mega 2560. For those unfamiliar, video on the Arduino is actually somewhat of a solved problem – merely requiring a ...

and Mega 2560 don't support the Debugger feature as they're powered by an AVR microcontroller. How Are The Boards Used With ...