It's blue! It's thin (0.8mm)! It's the Arduino Pro Mini! This is a 5V Arduino running the 16MHz bootloader (select 'Arduino Duemilanove w/ 328' within the Arduino software). Arduino Pro Mini does not come with connectors populated so that you can solder in any connector or wire with any orientation you need. We recommend first time Arduino users start with the Duemilanove. It's a great board that will get you up and running quickly. The Arduino Pro series is meant for users that understand the limitations of system voltage (5V), lack of connectors, and USB off board.
The Arduino Pro Mini is like the Arduino Mini (same pin out) but using all SMD components and made with two layers. This board connects directly to a FTDI Basic Breakout board and supports auto-reset. The Arduino Pro Mini also works with the FTDI cable but the FTDI cable does not bring out the DTR pin so the auto-reset feature will not work.
Dimensions: 0.7x1.3" (18x33mm)
ATmega328 running at 16MHz with external resonator (0.5% tolerance)