NANO v3.0 ATMEGA328P is a surface mount breadboard embedded version with integrated USB. It is a smallest, complete, and breadboard friendly. It has everything that DIECIMILA / DUEMILANOVE has (electrically) with more analog input pins and on board 5 volts jumper. Physically, it is absent power jack. The NANO is automatically sense and switch to the higher potential source of power, there is no need for the power select jumper.
Nano's got the breadboard-ability of the mini USB with smaller footprint than either, so users have more breadboard space. It's got a pin layout that works well with the mini or the basic stamp (TX, RX, ATN, GND on one top, power and ground on the other).
This new version 3.0 comes with ATMEGA328 which offer more prograing and data memory space. It is two layers. That make it easier to hack and more affordable., Hardware Specifications: Using ATMEL ATMEGA328p-au single chip support usb download and electricity supply support external dc5v-12v electricity supply support 9v battery electricity supply 12 digital input/output ports,d2-d13 8 analog input ports,a0-a7 a pair of level a serial port to send-receive port, rx/tx 6 pwm ports: d3,d5,d6,d9,d10,d11 support isp download