The Arduino Uno is the latest Arduino, released in late September 2010. It shares the same form factor and pin layout as its most recent predecessor, the Arduino Duemilanove, with a few updates.

From the Arduino website:

“The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used asPWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USBconnection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega8U2 programmed as a USB-to-serial converter.

“Uno” means one in Italian and is named to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 will be the reference versions of Arduno, moving forward. The Uno is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform; for a comparison with previous versions, see the index of Arduino boards.”

The Arduino Uno comes in a brand new, snazzy box, along with stickers.

Specifications

• Microcontroller: ATmega328
• Operating Voltage: 5V
• Input Voltage (recommended): 7-12V
• Input Voltage (limits): 6-20V
• Digital I/O Pins: 14 (of which 6 provide PWM output)
• Analog Input Pins: 6
• DC Current per I/O Pin: 40 mA
• DC Current for 3.3V Pin: 50 mA
• Flash Memory: 32 KB (ATmega328) of which 0.5 KB used by bootloader
• SRAM: 2 KB (ATmega328)
• EEPROM: 1 KB (ATmega328)
•  Clock Speed: 16 MHz 

Tutorials/Blogs

• GPS for Arduino in Less Than 30 Minutes 
• Arduino with Radio Shack Parallax accelerometer 
• Arduino with Parallax Sonar Sensor
• Uploading the driver
• Download the Arduino Antipasto IDE
• Datasheet

              Arduino Uno (front view)

              Arduino Uno (Back View)