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.

The Arduino Mega is a useful tool for the maker. Generally, once one has come up with plans for blinking LEDs that require more IO than is available on the Arduino Uno, one graduates to the Mega ...