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.

Go to Tools > Board > Arduino Mega 2560 6. Select the correct COM Port under Tools > Port 7. Click the Upload button. Issues & Fixes • Nothing is displayed on the LCD • Check all connections and ...

Meanwhile, the Arduino Mega is getting the same USB chip along with an ATMega2560 processor with twice the memory. Right now only 128K is available, but that's a software limitation and they're ...