Source: arduino.cc

Arduino YÚN is the first member of a new groundbreaking line of wifi products combining the power Linux with ease of use of Arduino. The first Arduino YÚN is the combination of a classic Arduino Leonardo (based on the Atmega32U4 processor) with a Wifi system-on-a-chip running Linino (a MIPS GNU/Linux based on OpenWRT).

It has embedded the Linux machine directly on the PCB of the Arduino Leonardo and has connected the two so that from Arduino it’s very easy to run commands on the Linux side and use it as an Ethernet and Wifi interface.

Historically, interfacing Arduino with complex web services has been quite a challenge due to the limited memory available. Web services tend to use verbose text based formats like XML that require quite a lot or ram to parse. On the Arduino YÚN a Bridge library has been created which delegates all network connections and processing of HTTP transactions to the Linux machine.

ArduinoYUNFront_450px

Image source: arduino.cc

Specifications:

Microcontroller ATmega32u4
Operating Voltage 5V
Input Voltage (recommended) 5V via microUSB or PoE 802.3af
Input Voltage (limits) 6-20V
Digital I/O Pins 14
PWM Channels 7
Analog Input Channels 6 (plus 6 multiplexed on 6 digital pins)
DC Current per I/O Pin 40 mA
DC Current for 3.3V Pin 50 mA
Flash Memory 32 KB (ATmega32u4) of which 4 KB used by bootloader
SRAM 2.5 KB (ATmega32u4)
EEPROM 1 KB (ATmega32u4)
Clock Speed 16 MHz
Processor MIPS 24K operating at up to 400 MHz
Memory DDR2 64MB Ram and 16 MB SPI Flash
AP or router Complete IEEE 802.11bgn 1×1
Host/Device USB 2.0
MicroSD PoE compatible 802.3af card support

Source: arduino.cc